Holding(s) in Company

NOTIFICATION OF MAJOR HOLDINGS (to be sent to the relevant issuer and to the FCA in Microsoft Word format if possible)ⁱ   1a. Identity of the issuer or the underlying issuer of existing shares to which voting rights are attachedⁱⁱ: Summit Therapeutics plc 1b. Please indicate if the issuer is a non-UK issuer  (please mark with an “X” if appropriate) Non-UK issuer   2. Reason for the notification (please mark the appropriate box or boxes with an “X”) An acquisition or disposal of voting rights X An acquisition or disposal of financial instruments   An event changing the breakdown of voting rights X Other (please specify)ⁱⁱⁱ:   3. Details of person subject to the notification obligation^iv Name Chelverton Asset Management Limited City and country of registered office (if applicable) Bath, United Kingdom 4. Full name of shareholder(s) (if different from 3.)^v Name Northern Trust CI01 City and country of registered office (if applicable)   5. Date on which the threshold was crossed or reached^vi: 9 January 2019 6. Date on which issuer notified (DD/MM/YYYY): 10 January 2019 7. Total positions of person(s) subject to the notification obligation   % of voting rights attached to shares (total of 8. A) % of voting rights through financial instruments
(total of 8.B 1 + 8.B 2) Total of both in % (8.A + 8.B) Total number of voting rights of issuer^vii Resulting situation on the date on which threshold was crossed or reached 2.81 %   2.81 % 160,389,881 Position of previous notification (if
applicable) 5.17 %      

8. Notified details of the resulting situation on the date on which the threshold was crossed or reached^viii A: Voting rights attached to shares Class/type of
shares
ISIN code (if possible) Number of voting rights^ix % of voting rights Direct
(Art 9 of Directive 2004/109/EC) (DTR5.1) Indirect
(Art 10 of Directive 2004/109/EC) (DTR5.2.1) Direct
(Art 9 of Directive 2004/109/EC) (DTR5.1) Indirect
(Art 10 of Directive 2004/109/EC) (DTR5.2.1) Common Stock GBp1 GB00BN40HZ01 4,500,000   2.81 %                       SUBTOTAL 8. A 4,500,000 2.81 %  

 

B 1: Financial Instruments according to Art. 13(1)(a) of Directive 2004/109/EC (DTR5.3.1.1 (a)) Type of financial instrument Expiration
date^x Exercise/
Conversion Period^xi Number of voting rights that may be acquired if the instrument is
exercised/converted. % of voting rights                                   SUBTOTAL 8. B 1      

 

B 2: Financial Instruments with similar economic effect according to Art. 13(1)(b) of Directive 2004/109/EC (DTR5.3.1.1 (b)) Type of financial instrument Expiration
date^x Exercise/
Conversion Period ^xi Physical or cash
settlement^xii Number of voting rights % of voting rights                                           SUBTOTAL 8.B.2      

 

 

9. Information in relation to the person subject to the notification obligation (please mark the
applicable box with an “X”) Person subject to the notification obligation is not controlled by any natural person or legal entity and does not control any other undertaking(s) holding directly or indirectly an interest in the (underlying) issuer^xiii   Full chain of controlled undertakings through which the voting rights and/or the
financial instruments are effectively held starting with the ultimate controlling natural person or legal entity^xiv (please add additional rows as necessary) X Name^xv % of voting rights if it equals or is higher than the notifiable threshold % of voting rights through financial instruments if it equals or is higher than the notifiable threshold Total of both if it equals or is higher than the notifiable threshold David, Mary, Thomas and Harry Horner       Chelverton Asset Management Holdings Limited       Chelverton Asset Management Limited                 10. In case of proxy voting, please identify: Name of the proxy holder   The number and % of voting rights held   The date until which the voting rights will be held     11. Additional information^xvi