SECURITIES PURCHASE AGREEMENT This SECURITIES PURCHASE AGREEMENT (this Agreement ) is made and entered into as of

SECURITIES PURCHASE AGREEMENT

This SECURITIES PURCHASE AGREEMENT (this Agreement ) is made and entered into as of February 2, 2024 by and among

Silence Therapeutics plc, a public limited company incorporated under the laws of England and Wales (the Company ), and the Investors identified on Exhibit A attached hereto (each an Investor and

collectively the Investors ).

A. The Company and the Investors are executing and delivering this Agreement in reliance upon the exemption from securities registration

afforded by the provisions of Section 4(a)(2) of the 1933 Act (as defined below) and Rule 506 of Regulation D ( Regulation D ) as promulgated by the SEC (as defined below) under the 1933 Act.

B. The Investors wish to purchase from the Company, and the Company wishes to sell and issue to the Investors, upon the terms and subject to

the conditions stated in this Agreement, an aggregate of 5,714,286 (the Private Placement ADSs ) American Depositary Shares of the Company ( ADSs ), each representing three ordinary shares of nominal value

0.05 each in the share capital of the Company (the Ordinary Shares ).

C. The Private Placement ADSs will be

issued pursuant to that certain deposit agreement, dated as of September 4, 2020 (the Deposit Agreement ), by and among the Company, The Bank of New York Mellon as depositary (the Depositary ), and all

Holders and Beneficial Owners of ADSs issued thereunder. The Company shall, following subscription by the Investors of the Private Placement ADSs, deposit, on behalf of the Investors, the Ordinary Shares underlying the Private Placement ADSs (the

Private Placement Shares ) with The Bank of New York Mellon, Manchester, as custodian for the Depositary (the Custodian ), which shall issue and deliver the Private Placement ADSs to the Investors.

D. References in this Agreement to (1) the Company issuing and selling ADSs to the Investors, and similar or analogous expressions, shall

be understood to include references to the Company allotting and issuing the new Ordinary Shares underlying those ADSs to the Custodian and procuring the issue of ADSs representing such Ordinary Shares by the Depositary or its nominee to the

relevant Investors; and (2) the purchase of, or payment for, any ADSs, and similar or analogous expressions, shall be understood to refer to the subscription for the Ordinary Shares underlying those ADSs, as well as deposit of the Ordinary

Shares for ADSs representing such Ordinary Shares, and the payment of the subscription moneys in respect of such Ordinary Shares.

Contemporaneously with the sale of the Private Placement ADSs, the parties hereto will execute and deliver a Registration Rights Agreement, substantially in the form attached hereto as Exhibit B (the Registration

Rights Agreement ), pursuant to which the Company will agree to provide certain registration rights in respect of the Private Placement Shares under the 1933 Act.

In consideration of the mutual promises made herein and for other good and valuable consideration, the receipt and sufficiency of which are

hereby acknowledged, the parties hereto agree as follows:

1. Definitions. For the purposes of this Agreement, in addition to the terms defined

above, the following terms shall have the meanings set forth below:

1933 Act means the Securities Act of 1933, as

amended, or any successor statute, and the rules and regulations promulgated thereunder.

1934 Act means the Securities

Exchange Act of 1934, as amended, or any successor statute, and the rules and regulations promulgated thereunder.

means American Depositary Receipts.

Affiliate means, with respect to any Person, any other Person which directly or

indirectly through one or more intermediaries Controls, is controlled by, or is under common Control with such Person.

Authorizations has the meaning set forth in Section .

Business Day means a day, other than a Saturday or Sunday, on which banks in New York City are open for the general

transaction of business.

Closing has the meaning set forth in Section .

Closing Date has the meaning set forth in Section .

Code means the Internal Revenue Code of 1986, as amended.

Company Covered Person means, with respect to the Company as an issuer for purposes of Rule 506 promulgated

under the 1933 Act, any Person listed in the first paragraph of Rule 506(d)(1).

Company s Knowledge means the

actual or constructive knowledge of any director or executive officer (as defined in Rule 405 under the 1933 Act) of the Company.

Companies Act means the UK Companies Act 2006.

Control (including the terms controlling, controlled by or under common control with )

means the possession, direct or indirect, of the power to direct or cause the direction of the management and policies of a Person, whether through the ownership of voting securities, by contract or otherwise.

Disqualification Event has the meaning set forth in Section 4.35.

Employee Benefit Plan means each plan, fund, policy, program, arrangement or agreement, including any fringe benefit plan

or program, health, medical, dental and life insurance benefits, disability benefits, bonus or incentive plan, option, restricted share, equity or share based award, bonus, vacation pay, bonus program, service award, relocation or moving expense,

deferred bonus plan, severance plan, salary continuation plan, salary reduction agreement, retirement or pension plan, deferred compensation plan, change-of-control

agreement, employment agreement or consulting agreement, which in each case, is sponsored, maintained or contributed to (or is required to be sponsored, maintained or contributed to) by the Company for the benefit of any current or former directors,

officers, employees, consultants, independent contractors or other individual service providers of a the Company.

Exempt Issuance has the meaning set forth in Section .

FSMA means the UK Financial Services and Markets Act 2000.

IFRS has the meaning set forth in Section .

Investor Materials means the information package provided to Investors in connection with this Agreement.

Governmental Authority means any federal, state, local or foreign government or political subdivision thereof, or any

agency or instrumentality of such government or political subdivision, or any self-regulated organization or other non-governmental regulatory authority or quasi-governmental authority (to the extent that the

rules, regulations or orders of such organization or authority have the force of law), or any arbitrator, court or tribunal of competent jurisdiction.

Intellectual Property has the meaning set forth in Section .

Investor Questionnaire means the Investor Questionnaire substantially in the form attached hereto as Exhibit C.

Lock-Up Period has the meaning set forth in Section .

Material Adverse Effect means any event, occurrence, fact, condition or change that is, or could reasonably be expected to

become, individually or in the aggregate, materially adverse to (i) the assets, liabilities, results of operations, prospects, condition (financial or otherwise) or business of the Company and its subsidiaries taken as a whole, (ii) the

legality or enforceability of any of the Transaction Documents or (iii) the ability of the Company to perform its obligations under the Transaction Documents, except that for purposes of Section 6.1(g) of this

Agreement, in no event shall a change in the market price of the Ordinary Shares or ADSs alone constitute a Material Adverse Effect (provided that the underlying causes of such a change may be taken into account in determining whether a

Material Adverse Effect has occurred).

Material Contract means any contract, instrument or other agreement to which

the Company is a party or by which it is bound that has been filed or was required to have been filed as an exhibit to the SEC Filings pursuant to Item 601(b)(4) or Item 601(b)(10) of Regulation S-K.

Maximum Percentage means 19.99% of the issued and outstanding Ordinary Shares (including Ordinary Shares represented

by ADSs) immediately after giving effect to the applicable purchase of Private Placement ADSs if exceeding that limit would result in a change of control under Nasdaq Listing Rule 5635(b) or any successor rule.

Nasdaq means the Nasdaq Global Market.

Ordinary Share Equivalents means any securities of the Company which

would entitle the holder thereof to acquire at any time Ordinary Shares, including those represented by ADSs, or, without limitation, any debt, preferred shares, rights, options, warrants or other instrument that are at any time convertible into or

exchangeable for, or otherwise entitles the holder thereof to receive, Ordinary Shares.

Person means an individual,

corporation, partnership, limited liability company, trust, business trust, association, joint stock company, joint venture, sole proprietorship, unincorporated organization, governmental authority or any other form of entity not specifically listed

Placement Agents means Morgan Stanley & Co. LLC, William Blair & Company, L.L.C., H.C.

Wainwright & Co. LLC and Chardan Capital Markets, LLC.

Press Release has the meaning set forth in

Principal Trading Market means the Trading Market on which the ADSs are primarily listed

for trading, which, as of the date of this Agreement and the Closing Date, is Nasdaq.

Prospectus Regulation means

Regulation (EU) 2017/1129.

Regulatory Authorities has the meaning set forth in Section .

Required Investors has the meaning set forth in the Registration Rights Agreement.

SEC means the U.S. Securities and Exchange Commission.

SEC Filings has the meaning set forth in Section .

Short Sales means all short sales as defined in Rule 200 of Regulation SHO under the 1934 Act (but shall not be

deemed to include the location and/or reservation of borrowable Ordinary Shares or ADSs).

Trading Day means (i) a

day on which the ADSs are listed on the Principal Trading Market, or (ii) if the ADSs are not listed on any Trading Market, a day on which the ADSs are quoted in the

over-the-counter market as reported in the pink sheets by OTC Markets Group Inc. (or any similar organization or agency succeeding to its functions of

reporting prices); provided, that in the event that the ADSs are not listed or quoted as set forth in (i) or (ii) hereof, then Trading Day shall mean a Business Day.

Trading Market means whichever of the New York Stock Exchange, the NYSE American, the Nasdaq Global Select Market, the

Nasdaq Global Market or the Nasdaq Capital Market on which the ADSs are listed for trading on the date in question.

Documents means this Agreement and the Registration Rights Agreement.

Transfer Taxes has the meaning set

UK Prospectus Regulation means the Prospectus Regulation as it forms part

of domestic law by virtue of the European Union (Withdrawal) Act 2018.

2. Purchase and Sale of the Private Placement ADSs.

On the Closing Date, upon the terms and subject to the conditions set forth herein, the Company will issue and sell, and the Investors will, severally and not jointly, purchase the number of Private Placement ADSs set forth opposite the name of such

Investor under the heading Number of Private Placement ADSs to be Purchased on Exhibit A attached hereto, at a price per ADS equal to $21.00.