Aon Global Holdings plc

The Aon Centre

The Leadenhall Building

122 Leadenhall Street

London, EC3V 4AN

the Prospectus Supplement;

a copy of the underwriting agreement of the Co-Issuers, the Guarantors, Morgan Stanley & Co. LLC, BofA Securities, Inc. and HSBC Securities (USA) Inc. dated 23 February 2023 (the Underwriting Agreement);

a copy of the current Articles of Association of AGH as at 28 February 2023;

a copy of AGH’s Certificate of Incorporation dated 16 September 2014, issued by the Registrar of Companies of England and Wales, together with a copy of AGH’s Certificate of Incorporation on re-registration of a private limited company as a public limited company dated 29 April 2020 ((c) and (d) together the AGH Constitutional Documents);

a copy of the current Articles of Association of AGL as at 28 February 2023;

a copy of AGL’s Certificate of Incorporation dated 8 December 2011, issued by the Registrar of Companies of England and Wales, together with copies of AGL’s Certificate of Incorporation on change of name dated 23 December 2011, Certificate of Incorporation on change of name and registration of a private company as a public company dated 30 March 2012 and Certificate of Incorporation on change of name and registration of a public company as a private company dated 15 July 2020 ((e) and (f) together the AGL Constitutional Documents and, together with the AGH Constitutional Documents, the Constitutional Documents);

a copy of the indenture dated 3 December 2018 entered into between the Co-Issuers, the Guarantors and the Bank of New York Mellon, as trustee, as supplemented by the amended and restated indenture dated 1 April 2020, as further supplemented by the second indenture supplement dated 2 December 2021, the third indenture supplement dated 28 February 2022, the fourth indenture supplement dated 12 September 2022 and the fifth indenture supplement dated 28 February 2023 under which the Debt Securities are to be issued (the Indenture) containing the guarantee of the Debt Securities by the Guarantors (the Guarantee) (the Indenture and the Underwriting Agreement together, the Documents);

searches carried out on 28 February 2023 with respect to each of AGH and AGL (carried out by us or by LegalinX Limited trading as GlobalX on our behalf) of the public documents of AGH and AGL kept at Companies House in Cardiff (the Company Searches);

a winding up enquiry of the Central Registry of Winding up Petitions (carried out by us or by GlobalX on our behalf) on 28 February 2023 with respect to each of AGH and AGL (the Winding-up Enquiry);

a certificate issued to us by the Company Secretary of AGH dated 28 February 2023 (the AGH Secretary’s Certificate);

a certificate issued to us by the Company Secretary of AGL dated 28 February 2023 (the AGL Secretary’s Certificate and together with the AGH Secretary’s Certificate, the Secretaries’ Certificates);

written resolutions of the board of directors of AGH approved on 21 February 2023 authorising the execution and delivery of and performance of obligations under the Indenture, the issue of term debt by AGH as a Co-Issuer and the execution and delivery of and performance of obligations under the Debt Securities; and

written resolutions of the board of directors of AGL approved on 21 February 2023 authorising the execution and delivery of and performance of obligations under the Indenture and the execution and delivery of and performance of obligations under, when issued, the Debt Securities and the Guarantee,

Authenticity: (A) the genuineness of all signatures, (B) that a signatory has personally signed each Document either (i) by hand (a wet ink signatory); or (ii) by adding an image or their signature to an electronic version of the Document; or (iii) by adding their signature to an electronic version of the Document on an approved web-based electronic signing platform (e-platform) contemplated by the parties; or (iv) by using a mouse, finger, stylus or similar to sign their name in an electronic version of the Document on a touchscreen device such as an iPad (each signature referred to in (ii) to (iv) an e-signature, and each signatory referred to in (ii) to (iv) an e-signatory), and (C) the genuineness of all stamps and seals on, and the authenticity, accuracy and completeness of, all documents submitted to us (whether as originals or copies);

Copies: the conformity to originals of all documents supplied to us as photocopies, portable document format (PDF) copies, facsimile copies or e-mail conformed copies;

Witnessing: that where a document has been witnessed, each witness has personally witnessed the signature of that document by the person whose signature they are witnessing and has applied its own witness signature or authorised its witness signature to be appended to the final text or any electronic version of the final text of the document only after doing so;

Virtual Signings: that the parties have complied with the procedures for counterpart signature and delivery of the Documents contemplated by the parties and their legal advisers and that the parties have validly authorised the attachment of their respective signature pages to the final texts of the Documents;

Confirmation by Counsel: in any case where a party’s counsel has attached and released the signature pages of that party’s counterparts of the Documents, that such counsel had all necessary authority from that party to do so;

Drafts: that, where a document has been examined by us in draft or specimen form, it will be or has been executed in the form of that draft or specimen;

Secretaries’ Certificates: that each of the statements contained in the Secretaries’ Certificates is true and correct as at the date hereof;

Written Resolutions: that the written resolutions approved by AGL on 21 February 2023, as evidenced by the written resolutions included in the AGL Secretary’s Certificate, were properly passed, that all provisions contained in the Companies Act 2006 and the Articles of Association of AGL relating to the disclosure of directors’ interests and the power of interested directors to vote were duly observed, and that such resolutions have not been amended, modified or revoked and are in full force and effect; the directors of AGL having any interest in any of the matters duly disclosed their interest therein and were entitled to approve the written resolutions; and such resolutions remain in full force and effect without modification;

Written Resolutions: that the written resolutions approved by AGH on 21 February 2023, as evidenced by the written resolutions included in the AGH Secretary’s Certificate, were properly passed, that all provisions contained in the Companies Act 2006 and the Articles of Association of AGH relating to the disclosure of directors’ interests and the power of interested directors to vote were duly observed, and that such resolutions have not been amended, modified or revoked and are in full force and effect; the directors of AGH having any interest in any of the matters duly disclosed their interest therein and were entitled to approve the written resolutions; and such resolutions remain in full force and effect without modification;

Corporate Power: that each of the parties to the Documents (other than AGH and AGL) has the necessary capacity and corporate power to execute, deliver and perform its obligations under the Documents, and that the Documents have been duly authorised and executed and delivered by each of the parties thereto in accordance with all applicable laws (other than in the case of AGH and AGL, the laws of England) in the form filed as an exhibit to the Registration Statement;

Validity under all laws: that the Documents and, when issued, the Debt Securities constitute legal, valid and binding obligations of each of the parties thereto enforceable under all applicable laws including the laws of the United States and the laws of the State of New York by which they are expressed to be governed (other than in the case of AGH and AGL, the laws of England); that satisfactory evidence of the laws of the United States and the State of New York, which is required to be pleaded and proved as a fact in any proceedings before the English Courts, could be so pleaded and proved; and that insofar as the laws and regulations of any other jurisdiction may be relevant to (i) the obligations or rights of any of the parties under the Documents, or (ii) any of the transactions contemplated by the Documents, such laws and regulations do not prohibit, and are not inconsistent with, the entering into and performance of any such obligations, rights or transactions;

Filings under all laws: that all consents, licences, approvals, notices, filings, recordations, publications and registrations which are necessary under any applicable laws (other than, in the case of AGH and AGL, the laws of England) in order to permit the execution, delivery or performance of the Documents or to perfect, protect or preserve any of the interests created by the Documents, have been made or obtained, or will be made or obtained within the period permitted or required by such laws or regulations;

No Amendments: that the Documents have not been amended, terminated, rescinded or varied, that there has been no breach of any of its provisions by any of the parties thereto which would affect the opinions expressed in this opinion, and that the Documents are not affected in any way by any relevant provisions of any other document or agreement or any course of dealings between the parties thereto;

Unknown Facts: that there are no facts or circumstances (and no documents, agreements, instruments or correspondence) which are not apparent from the face of the documents we have reviewed or which have not been disclosed to us that may affect the validity or enforceability of the Documents or any obligation therein or otherwise affect the opinions expressed in this opinion;

Arm’s Length Terms: that the Documents have been entered into for bona fide commercial reasons and on arm’s length terms by each of the parties thereto;

Directors’ Duties: that the directors of AGL and AGL in authorising the execution and delivery of and performance of obligations under the Documents and, when issued, the Debt Securities have exercised their powers in accordance with their duties under all applicable laws and the Constitutional Documents, as applicable, in force at the applicable time;

FSMA: that the sale of the Debt Securities or the consummation by AGH and AGL of the transactions contemplated by the Documents (as relevant) will not constitute an “offer to the public” within the meaning of Part VI of the Financial Services and Markets Act 2000 (the FSMA) and does not require the publication by the Co-Issuers of a prospectus pursuant to Onshored Regulation (EU) 2017/1129, as it forms part of the laws of the United Kingdom by virtue of the European Union (Withdrawal) Act 2018;

Authorisation under FSMA: that each person dealing with AGH and/or AGL in connection with the Debt Securities which is carrying on, or purporting to carry on, a regulated activity (within the meaning of section 19 of the Financial Services and Markets Act 2000) is an authorised person or an exempt person for the purposes of the FSMA;

FSMA (Financial promotion): that the Registration Statement and the Prospectus Supplement (including any such document in draft and preliminary form) and any other invitation or inducement to engage in investment activity (within the meaning of section 21 of the FSMA) in connection with the issue or sale of the Debt Securities has only been and will only be communicated or caused to be communicated in circumstances in which section 21(1) of the FSMA does not apply to AGH and/or AGL;

Company Searches: that the information revealed by the Company Searches: (i) was accurate in all respects and has not since the time of such search been altered; and (ii) was complete, and included all relevant information which had been properly submitted to the Registrar of Companies;

Winding up Enquiry: that the information revealed by our Winding-up Enquiry was accurate in all respects and has not since the time of such enquiry been altered;

Representations: that the terms of the Documents and Underwriting Agreement, other than, in the case of the Underwriting Agreement, as to matters of law on which we opine in this opinion, have been and will be observed and performed by the parties thereto;

Financial crime, national security and investment, antitrust and criminal cartel, sanctions, pensions and human rights etc: that the parties to the Documents and all persons representing them have complied (and will continue to comply) with all applicable anti-terrorism, national security and investment laws, anti-corruption, anti- money laundering, anti-tax evasion, other financial crime, civil or criminal antitrust, cartel, competition, public procurement, state aid, anti-subsidy, sanctions, pensions and human rights laws and regulations which may affect them, the transactions contemplated by the Documents or the Documents, and that performance and enforcement of them, the transactions contemplated by the Documents or the Documents is, and will continue to be, consistent with all such laws and regulations; and

Bad Faith, Fraud, Duress: the absence of bad faith, breach of duty, breach of trust, fraud, coercion, duress or undue influence on the part of any of the parties to the Documents and their respective directors, employees, agents and advisers (excepting ourselves).

Corporate Existence: AGH has been duly incorporated in the United Kingdom and registered in England and Wales as a public limited company and AGL has been duly incorporated in the United Kingdom and registered in England and Wales as private limited company;

Corporate Power: (i) AGH has the requisite corporate power and capacity to issue, deliver and perform its obligations under, when issued, the Debt Securities in accordance with the terms of the Indenture and (ii) AGL has the requisite corporate power and capacity to issue, deliver and perform its obligations under, when issued, the Guarantee, in accordance with the terms of the Guarantee and the Indenture;

Corporate Authority: (i) AGH has taken steps required under English law and the AGH Constitutional Documents to authorise AGH to enter into and perform its obligations under, when issued, the Debt Securities in accordance with the terms of the Indenture and (ii) AGL has taken steps required under English law and the AGL Constitutional Documents to authorise AGL to enter into and perform its obligations under, when issued, the Guarantee in accordance with the terms of the Indenture; and

No Violation: the execution and delivery of the Debt Securities and the Documents and the performance of AGH’s and AGL’s obligations thereunder (in accordance with the terms of the relevant Document) have been respectively duly authorised by all necessary corporate action on the part of AGH and AGL and do not and will not of themselves result in any violation by AGH or AGL of any term of their respective Constitutional Documents or of any law or regulation having the force of law in England and applicable to AGH or AGL as to performance.

Company Searches: the Company Searches are not capable of revealing conclusively whether or not:

a winding-up order has been made or a resolution passed for the winding- up of a company; or

an administration order has been made; or

a receiver, administrative receiver, administrator or liquidator has been appointed; or

a court order has been made under the Cross-Border Insolvency Regulations 2006,

Winding up Enquiry: the Winding-up Enquiry relates only to the presentation of: (i) a petition for the making of a winding-up order or the making of a winding-up order by the court, (ii) an application to the High Court of Justice in London for the making of an administration order and the making by such court of an administration order, (iii) a notice of intention to appoint an administrator or a notice of appointment of an administrator filed at the High Court of Justice in London, and (iv) a notice of a moratorium under Part A1 of the Insolvency Act 1986. It is not capable of revealing conclusively whether or not such a winding-up petition, application for an administration order, notice of intention, notice of appointment or notice of a moratorium has been presented or winding-up or administration order granted, because:

details of a winding-up petition or application for an administration order may not have been entered on the records of the Central Registry of Winding-up Petitions immediately;

in the case of (A) an application for the making of an administration order; (B) the filing of a notice of intention to appoint an administrator; (C) the filing of a notice of appointment of an administrator; or (D) the filing of a notice of a moratorium, if such application is made to, order made by or notice filed with, a court other than the High Court of Justice in London, no record of such application, order or notice will be kept by the Central Registry of Winding-up Petitions;

a winding-up order or administration order may be made before the relevant petition or application has been entered on the records of the Central Registry, and the making of such order may not have been entered on the records immediately;

details of a notice of intention to appoint an administrator or a notice of appointment of an administrator under paragraphs 14 and 22 of Schedule B1 of the Insolvency Act 1986 may not be entered on the records immediately (or, in the case of a notice of intention to appoint, at all); and

with regard to winding-up petitions, the Central Registry of Winding-up Petitions may not have records of winding-up petitions issued prior to 1994;

Foreign Courts: no opinion is given as to whether or not the chosen court will take jurisdiction (applying its own conflict rules), or act in accordance with the parties’ agreement as to choice of law or whether the English courts would grant a stay of any proceedings commenced in England, or whether the English courts would grant any ancillary relief in relation to proceedings commenced in a foreign court;

Financial Limitations: no opinion is given as to the compliance or otherwise with: (i) the financial limitations on borrowings or covenants by each of AGH and AGL contained in the relevant Constitutional Documents; or (ii) the limitations on the maximum aggregate principal amount of the Debt Securities which may be issued by the Co-Issuers and irrevocably guaranteed by the Guarantors as contemplated by the Registration Statement; and

Insolvency: this opinion is subject to all applicable laws relating to insolvency, bankruptcy, administration, moratorium, reorganisation, liquidation or analogous circumstances and other similar laws of general application relating to or affecting generally the enforcement of creditor’s rights and remedies from time to time.