THIS DOCUMENT IS IMPORTANT AND REQUIRES YOUR IMMEDIATE ATTENTION. If you are in any doubt as to any aspect of the proposals referred to in this notice or as to the action you should take, please take advice from a stockb

THIS DOCUMENT IS IMPORTANT AND REQUIRES YOUR IMMEDIATE ATTENTION.

If you are in any doubt as to any aspect of the proposals referred to in this notice or as to the action you should take, please take advice from a

stockbroker, solicitor, accountant or other independent professional adviser.

If you have sold or otherwise transferred all of your shares, please send

this document, together with the enclosed documents, at once to the purchaser or transferee, or to the stockbroker, bank or other agent through whom the sale or transfer was effected for transmission to the purchaser or transferee.

It is important that you submit your proxy vote electronically. Proxies may be submitted electronically using Link Group s Signal Shares share portal

service at www.signalshares.com or in hard copy form if you request a hard copy Form of Proxy from the Company s registrar, Link Group. In order to be valid, proxy appointments must be submitted using Link Group s Signal Shares share

portal service or in hard copy form to Link Group at PXS 1, 10th Floor, Central Square, 29 Wellington Street, Leeds LS1 4DL, in each case, by no later than 11.00 a.m on 25 May 2021 or 48 hours before any adjourned meeting. The electronic

appointment of a proxy using Link Group s Signal Shares share portal service or the completion and return of a Form of Proxy in hard copy form would ordinarily not preclude shareholders from attending and voting at the AGM should they so wish.

However, this is subject to the UK Government s COVID-19 measures summarised in paragraph 3 of the letter from the Chairman of the Company included in this document, which mean ordinary shareholders are

not expected to be allowed to attend the AGM in person. Any hard copy Form of Proxy should, to be valid, be completed and signed in accordance with the instructions printed on it.

If you require a hard copy Form of Proxy (or assistance with how to complete, sign and return it) or assistance in submitting your proxy appointment

electronically, please call Link Group on +44 (0)371 664 0300. Calls are charged at the standard geographic rate and will vary by provider. Calls from outside the UK will be charged at the applicable international rate. Lines are open 9.00 a.m. to

5.30 p.m., Monday to Friday, excluding public holidays in England and Wales.

If you hold your ordinary shares in uncertificated form (i.e. in CREST), you

may appoint a proxy for the AGM by completing and transmitting a CREST Proxy Instruction in accordance with the procedures set out in the CREST Manual issued by Euroclear so that it is received by the registrar (under CREST Participation ID RA10) by

no later than 11.00 a.m. on 25 May 2021. The time of receipt will be taken to be the time from which the registrar is able to retrieve the message by enquiry to CREST in the manner proscribed by CREST.

A copy of this document will also be available on the Company s website, www.mereobiopharma.com/agm2021

NOTICE OF THE ANNUAL GENERAL MEETING

OF MEREO BIOPHARMA GROUP PLC

to be held at the 4th Floor, One Cavendish Place, London W1G 0QF, United Kingdom

on 27 May 2021 at 11.00 a.m. (London time) (the AGM )

Cautionary note regarding forward-looking statements

This document contains statements about the Company that are or may be forward-looking statements . All statements, other than statements of

historical facts, included in this document may be forward-looking statements. Without limitation, any statements preceded or followed by, or that include, the words targets , plans , believes , expects ,

aims , intends , will , may , should , anticipates , estimates , projects or words or terms of similar substance, or the negative thereof, are forward-looking

statements. These forward-looking statements are not guarantees of future performance and have not been reviewed by the auditors of the Company. These factors are discussed in the Risk Factors section of the Company s annual reports

and accounts and filings that the Company makes with the Securities and Exchange Commission, including its Annual Report on Form 20-F for the year ended 31 December 2020 and subsequent reports of Form 6-K. These forward-looking statements involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of any such person, or industry results, to be

materially different from any results, performance or achievements expressed or implied by such forward-looking statements. These forward-looking statements are based on numerous assumptions regarding the present and future business strategies of

such persons and the environment in which each will operate in the future. Past performance is not a guarantee of future performance. Investors should not place undue reliance on such forward-looking statements and, save as is required by law or

regulation, the Company does not undertake any obligation to update publicly or revise any forward-looking statements (including to reflect any change in expectations with regard thereto or any change in events, conditions or circumstances on which

any such statement is based). All subsequent forward-looking statements attributed to the Company or any persons acting on its behalf are expressly qualified in their entirety by the cautionary statement above. All forward-looking statements

contained in this document are based on information available to the Directors of the Company at the date of this document, unless some other time is specified in relation to them, and the posting or receipt of this document shall not give rise to

any implication that there has been no change in the facts set forth herein since such date.

Notice to overseas persons

The distribution of this document in certain jurisdictions may be restricted by law and therefore persons into whose possession this document comes should

inform themselves about and observe any such restrictions. Any failure to comply with these restrictions may constitute a violation of the securities laws of any such jurisdiction.

Letter from the Chairman of Mereo BioPharma Group plc

(Registered and incorporated in England and Wales with Company number 09481161)

Notice of 2021 Annual General Meeting

The purpose of this document is to

provide you with details of the Annual General Meeting ( AGM ) of the Company to be held on 27 May 2021 at 11.00 a.m. (London time) and convened by the formal Notice of Annual General Meeting set out on page 8 of this document.

This letter also explains the resolutions which will be considered at the AGM, why the Directors consider the resolutions to be in the best interests of

shareholders of the Company as a whole and why they recommend that you vote in favour of the resolutions.

2. Business of the AGM

The business to be conducted at the AGM consists of consideration of the following resolutions. Resolutions 1 to 12 (inclusive) are proposed as ordinary

resolutions. This means that for each of those resolutions to be passed, more than half of the votes cast must be in favour of the resolution.

Resolution 1 2020 Annual Report and Accounts

This resolution is proposed as an ordinary resolution.

Directors are obliged to lay the annual financial statements, the directors report and the independent auditor s report before shareholders each financial year at a general meeting.

The Company s annual financial statements, the directors report and the independent auditor s report for the financial year ended

31 December 2020 will be sent to and/or made available to shareholders from 16 April 2021 and can be accessed at www.mereobiopharma.com/investors

Resolutions 2 and 3 Appointment and remuneration of Ernst & Young LLP

These resolutions are proposed as ordinary resolutions.

Company is required to appoint auditors at each general meeting at which accounts are laid before the shareholders to hold office until the next such meeting. At the Company s accounts meeting held on 28 September 2020, Ernst &

Young LLP were re-appointed as auditors to hold office from the conclusion of that meeting until the conclusion of the forthcoming AGM.

Resolution 2 proposes the re-appointment of Ernst & Young

LLP as auditors of the Company.

Resolution 3 authorises the Directors to determine Ernst & Young LLP s remuneration.

Ernst & Young LLP have indicated that they are willing to act as the Company s auditors until the conclusion of the Company s next annual

general meeting at which the Company s annual report and accounts are presented.

Resolutions 4 and 5 Directors remuneration

report and Directors remuneration policy These resolutions are proposed as ordinary resolutions.

Resolution 4 is to approve the

directors remuneration report, set out on pages 39 to 61 (inclusive) of the 2020 Annual Report and Accounts.

Following the Company s listing

in the U.S. on the Nasdaq Global Market in April 2019, the Companies Act 2006 requires that the directors remuneration report be subject to an annual advisory vote so that shareholders vote by way of ordinary resolution to approve the

directors remuneration in the relevant financial year and how the directors remuneration policy will be implemented in the following financial year. The vote is advisory in nature and no entitlement to remuneration is conditional on the

passing of the resolution.

Resolution 5 is to approve the directors remuneration policy set out in the directors remuneration report at pages

42 to 51 (inclusive) of the 2020 Annual Report and Accounts.

Following the Company s listing in the U.S. on the Nasdaq Global Market, the Companies

Act 2006 also requires that the directors remuneration policy be subject to a binding vote every three years. The directors remuneration policy was last approved at the Company s accounts meeting held on 28 September 2020.

However, in light of the cancellation of the Company s ordinary shares to trading on the AIM market of the London Stock Exchange in December 2020 and the Company continuing forward solely with its Nasdaq Global Market listing, the directors

have taken the opportunity during 2020 to further review the directors remuneration policy to ensure it remains optimized and fully aligned with the Company s strategy. Although, the Remuneration Committee has concluded that the current

overarching remuneration framework continues to be effective and that no significant changes to the structure are required at this stage, two changes are proposed to how the directors remuneration policy will operate. Both are aimed, primarily

at bringing the policy into line with typical U.S. practice. Firstly, the directors are proposing to rebalance the Chief Executive Officer s short- and long-term incentive arrangements such that the maximum cash bonus potential will reduce and

be offset by larger awards of longer-term equity incentives which vest over a four-year period. This change will more closely link incentives with the long-term strategy as well as increasing alignment between the Chief Executive Officer and

shareholders. Secondly, the directors are proposing to amend the policy on payment for loss of office in the event of a change of control. This change will ensure we have the appropriate flexibility to build in provisions typically found in U.S.

service contracts and to ensure we are limiting any potential adverse impact on the motivation, dedication and objectivity of our Chief Executive Officer in the event of a potential and/or actual change of control. In order to accommodate these two

changes, shareholder approval is being sought for approval of the revised directors remuneration policy.

The revised directors remuneration

policy, if approved, will take effect immediately after the end of the AGM. Further information about proposed changes to the policy can be found at page 39 of the 2020 Annual Report and Accounts, and in the directors remuneration policy on

pages 42 to 51 of the 2020 Annual Report and Accounts.

Resolutions 6, 7, 8, 9, 10, 11 and 12

Re-appointment of Dr. Jeremy Bender, Dr. Brian Schwartz, Dr. Peter Fellner, Dr. Denise Scots-Knight, Peter Bains, Dr. Anders Ekblom and Kunal Kashyap

These resolutions are proposed as ordinary resolutions.

Dr. Jeremy Bender and Dr. Brian Schwartz were appointed as directors of the Company on 1 October 2020. In accordance with Article 29.1(a) of

the Company s articles of association, at each annual general meeting any director in office who has been appointed by the Directors since the previous annual general meeting

shall retire from office but be eligible for re-appointment. A

biography for each of Dr. Jeremy Bender and Dr. Brian Schwartz is included in the 2020 Annual Report and Accounts published on 16 April 2020 and is available from the Company s Investor Relations website

(www.mereobiopharma.com/investors).

Each of Dr. Peter Fellner, Dr. Denise Scots-Knight, Peter Bains, Dr. Anders Ekblom and Kunal Kashyap

retired and were re-appointed as directors of the Company at the 2018 annual general meeting of the Company. In accordance with Article 29.1(b) of the Company s articles of association, any director in

office for whom the AGM is the third annual general meeting following the annual general meeting at which he was elected or last re-elected shall retire from office but be eligible for re-appointment.

The Directors believe that Dr. Jeremy Bender, Dr. Brian Schwartz, Dr. Peter Fellner,

Dr. Denise Scots-Knight, Peter Bains, Dr. Anders Ekblom and Kunal Kashyap bring a wealth of experience to the Board and therefore consider it entirely appropriate for them to seek re-appointment at

3. Attendance at the AGM