TR-1: Notification of Major Interest in Shares

10th Sep 2012 11:12

For filings with the FSA include the annex For filings with issuer exclude the annex

TR-1: NOTIFICATION OF MAJOR INTEREST IN SHARESi

1. Identity of the issuer or the underlying issuer Silence Therapeuticsof existing shares to which voting rights are

PLCattached:ii

2 Reason for the notification (please tick the appropriate box or boxes): An acquisition or disposal of voting rights x

An acquisition or disposal of qualifying financial instruments which may result

in the acquisition of shares already issued to which voting rights are attached

An acquisition or disposal of instruments with similar economic effect to qualifying financial instruments An event changing the breakdown of voting rights

Other (please specify):

3. Full name of person(s) subject to the Richard Griffithsnotification obligation:iii 4. Full name of shareholder(s)

(if different from 3.):iv

5. Date of the transaction and date on which the threshold is crossed or

6 September 2012reached: v

6. Date on which issuer notified: 10 September 2012 7. Threshold(s) that is/are crossed or

7%reached: vi, vii 8. Notified details:A: Voting rights attached to shares viii, ixClass/type of Situation previous Resulting situation after the triggeringshares to the triggering transaction transaction if possibleusingthe ISIN CODE Number Number Number Number of voting % of voting rights x of of of shares rights Shares Voting Rights Direct Direct xi Indirect Direct Indirect xiiGB0008433350 94,278,156 6.43% 103,881,856 103,881,856 7.09%Ordinary

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financial Expiration Exercise/ Number of voting % of votinginstrument date xiii Conversion Period rights that may be rights xiv acquired if the instrument is exercised/ converted.

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments xv, xvi

Resulting situation after the triggering transactionType of Exercise Expiration Exercise/ Number of voting % of voting rightsfinancial price date xvii Conversion rights instrument xix, xxinstrument period refers to xviii Nominal Delta Total (A+B+C)Number of voting rights Percentage of voting rights103,881,856 7.09%

9. Chain of controlled undertakings through which the voting rights and/or the

financial instruments are effectively held, if applicable: xxi

Proxy Voting: 10. Name of the proxy holder:

11. Number of voting rights proxy holder will cease

to hold:

12. Date on which proxy holder will cease to hold

voting rights: 13. Additional information: 14. Contact name: Chris Hill 15. Contact telephone number:

01481 738724

Note: Annex should only be submitted to the FSA not the issuer Annex: Notification of major interests in sharesxxii

A: Identity of the persons or legal entity subject to the notification

obligation Full name

(including legal form of legal entities)

Contact address

(registered office for legal entities)

Phone number & email Other useful information

(at least legal representative for legal persons)

B: Identity of the notifier, if applicable

Full name Contact address Phone number & email Other useful information (e.g. functional relationship with the person or legal entity subject to the notification obligation) C: Additional information

For notes on how to complete form TR-1 please see the FSA website.

XLON

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Related Shares:

SLN.L