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, 34 Beckenham Road, Beckenham, Kent BR3 4ZF, in each case, by no later than 11.00 a.m. on 30 January 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 General Meeting should they so wish. However,

this is subject to the UK Government s COVID-19 measures summarised in paragraph 4 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 General Meeting 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 0391. 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 General Meeting 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 30 January 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,

NOTICE OF GENERAL MEETING OF

MEREO BIOPHARMA GROUP PLC

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

on 1 February 2021 at 11.00 a.m. (London time) (the General Meeting )

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 2019 and subsequent reports on 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 General Meeting

The purpose of this document is to provide you with details of the General Meeting of the Company to be held on 1 February 2021 at 11.00 a.m. (London time)

and convened by the formal Notice of General Meeting set out on page 8 of this document.

This letter also explains the resolutions which will be

considered at the General Meeting, 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.

The business to be conducted at the General Meeting is limited to the following resolutions. Resolution 1 is proposed as an ordinary resolution. This means

that for this resolution to be passed, more than half of the votes cast must be in favour of the resolution. Resolution 2 is proposed as a special resolution. This means that for this resolution to be passed at least three-quarters of the votes cast

must be in favour of the resolution.

Resolution 1 Authority to allot shares

This resolution is proposed as an ordinary resolution.

the Companies Act 2006, the directors of a company may only exercise the powers of the Company to allot shares of the Company, or grant rights to subscribe for, or to convert securities into, shares of the Company (other than in connection with an

employee share scheme) if authorised to do so by the shareholders in a general meeting. The authority which is sought in respect of this is set out in Resolution 1, which would allow the Directors to allot new shares or grant rights to subscribe

for, or convert other securities into, shares up to an aggregate maximum nominal amount of 1,540,760.28, representing 150% of the issued share capital of the Company, as at 13 January 2021, being the latest practicable date prior to

publication of this document.

As at 13 January 2021, being the latest practicable date prior to publication of this document, the issued

share capital of the Company comprised ordinary shares with an aggregate nominal value of 1,027,173.52.

This authority is sought for the reasons

outlined in paragraph 3 below. If approved, the authority would expire on 30 June 2023, unless renewed, varied or revoked by the Company prior to that date.

Resolution 2 Disapplication of pre-emption rights

This resolution is proposed as a special resolution.

section 561(1) of the Companies Act 2006, if the Directors wish to allot ordinary shares, or grant rights to subscribe for, or convert securities into, ordinary shares (which for this purpose includes a sale of treasury shares) for cash, other than

pursuant to an employee share scheme, they must in the first instance offer them to existing ordinary shareholders in proportion to their holdings. There may be occasions, however, when the Directors need the flexibility to finance business

opportunities by the issue of shares for cash without a pre-emptive offer to existing shareholders, as noted in greater detail in paragraph 3 below. This cannot be done under the Companies Act 2006 unless the

shareholders have first waived their pre-emption rights.

Resolution 2 would allow the Directors to allot equity

securities for cash pursuant to the authority given by Resolution 1 without first being required to offer them to existing ordinary shareholders. If approved, the resolution would authorise the Directors to allot ordinary shares, or grant rights to

subscribe for, or convert securities into, ordinary shares up to an aggregate maximum nominal amount of 1,540,760.28 (which includes, for this purpose, the sale on a

non-pre-emptive basis of any shares held in treasury), representing 150% of the issued share capital of the Company calculated as at 13 January 2021, the latest

practicable date prior to the publication of this document, as if section 561(1) of the Companies Act 2006 did not apply to such allotment or grant or sale of treasury shares.

This power is sought for the reasons outlined in paragraph 3 below. If approved, the power would expire on 30 June 2023, unless renewed, varied or revoked by

the Company prior to that date.

In order to provide the Company with the flexibility to access additional capital to continue to implement the Company s strategy when market conditions

are appropriate, the Directors believe that it is in the best interests of the Company to be prepared in advance and have the ability to raise funds by issuing shares or other securities without the need to convene a general meeting should they

determine that it is appropriate to do so. The authority to allot shares and the power to allot equity securities for cash without a pre-emptive offer to existing ordinary shareholders granted at the 2020

annual general meeting were in an amount of 288,070.78, which represented 77% of the aggregate nominal amount of Company s share issued capital as at 26 May 2020 but would represent only 28% of the aggregate nominal amount of the

Company s share issued capital as at 13 January 2021, following the issue by the Company of new shares since May 2020. Accordingly, the authority and power proposed in Resolutions 1 and 2 would significantly increase the Directors

flexibility to access additional capital and would allow the Company to better compete for capital against other companies incorporated in the US and elsewhere which are not subject to allotment or pre-emption

restrictions such as those applicable to companies incorporated in England and Wales. Together with the Company s ADS listing on Nasdaq (which facilitates investment in the Company from a broad number of specialised US healthcare investors),

the Directors believe that this authority and power will significantly strengthen the Company s ability to compete with its competitors.

authority and power that will be granted to the Directors, if Resolutions 1 and 2 are passed, are primarily being requested to allow for the issue of shares (and, indirectly, ADSs), but would, if passed, also allow for the issue of other securities,

including, for example, awards granted under the Company s share schemes relating to non-employees.

Directors note that the authority and power granted to the Directors at the Company s 2019 annual general meeting were in an amount that represented 100% of the aggregate nominal amount of the Company s issued share capital as at 17 May

2019. However, this authority and power was limited to the period until the Company s 2020 annual general meeting. The authority and power proposed in Resolutions 1 and 2 would be in respect of a greater percentage of the current issued share

capital and would be limited to an extended 29 month period.

The authority and power proposed in Resolutions 1 and 2 would be in addition to the existing authorities and

powers granted to the Directors, including those granted at the Company s 2020 annual general meeting and those granted at the general meeting of the Company held on 30 June 2020 for the purposes of its June 2020 private placement offering

of $70 million. However, if the authority and power contemplated by Resolutions 1 and 2 are granted to the Directors, the Directors do not anticipate that the authority and power granted at the Company s 2020 annual general meeting will be

sought to be renewed or replaced at the 2021 annual general meeting.

The UK Government has introduced measures into English law restricting movement and gatherings to address the spread of

COVID-19. Among other things, the measures currently prohibit persons in Tier 4 areas from leaving or being outside of the place where they are living without reasonable excuse and (subject to certain

exceptions) from participating in gatherings consisting of two or more people in any indoor space. Every area of England is currently within the Tier 4 area. The Company and its shareholders are required to comply with these measures in the holding

of the General Meeting.

For the purposes of the General Meeting, a quorum is two qualifying persons, as determined in accordance with the Companies Act

2006. However, as things currently stand, it is expected that, as permitted under the Corporate Insolvency and Governance Act 2020, the General Meeting will be held as a closed meeting and ordinary shareholders will not be allowed to attend the

General Meeting in person. Accordingly, all shareholders are encouraged appoint the Chairman of the General Meeting as proxy to vote on the proposed resolutions in accordance with the instructions provided below. The Company will arrange for the