Holding(s) in Company

1. Identity of the issuer or the underlying issuerof existing shares to which voting rights areattached: ii

Plethora Solutions Holdings plc

2 Reason for the notification (please tick the appropriate box or boxes):

An acquisition or disposal of voting rights

YES

An acquisition or disposal of qualifying financial instruments which may result in the acquisition of shares already issued to which voting rights are attached

YES

An acquisition or disposal of instruments with similar economic effect to qualifying financial instruments

N/A

An event changing the breakdown of voting rights

N/A

Other (please specify):

3. Full name of person(s) subject to thenotification obligation: iii

Baker Bros. Advisors LP

4. Full name of shareholder(s)  (if different from 3.):iv

Baker Brothers Life Sciences, L.P. , 667, L.P., and 14159, L.P.

5. Date of the transaction and date onwhich the threshold is crossed orreached: v

September 19, 2014

6. Date on which issuer notified:

September 22, 2014

7. Threshold(s) that is/are crossed orreached: vi, vii

Above 3%

8. Notified details:

A: Voting rights attached to shares viii, ix

Class/type ofshares

if possible usingthe ISIN CODE

Situation previousto the triggeringtransaction

Resulting situation after the triggering transaction

NumberofShares

NumberofVotingRights

Numberof shares

Number of votingrights

% of voting rights x

Direct

Direct xi

Indirect xii

Direct

Indirect

Ordinary shares/

GB00B06GL868

4,500,000

4,500,000

61,739,056

61,739,056

9.77%

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financialinstrument

Expirationdate xiii

Exercise/Conversion Period xiv

Number of votingrights that may beacquired if theinstrument isexercised/ converted.

% of votingrights

Warrant to purchase ordinary shares at £0.15

September 19, 2019

5 years

28,619,528

4.33%

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

Resulting situation after the triggering transaction

Type of financialinstrument

Exercise price

Expiration date xvii

Exercise/Conversion period xviii

Number of voting rights instrument refers to

% of voting rights xix, xx

Nominal

Delta

Total (A+B+C)

Number of voting rights 90,358,584

Percentage of voting rights 13.67%*

9. Chain of controlled undertakings through which the voting rights and/or thefinancial instruments are effectively held, if applicable: xxi

Baker Bros. Advisors LP (the "Adviser") is the investment adviser of Baker Brothers Life Sciences, L.P., 14159, L.P., and 667, L.P. (collectively, the "Funds") and, pursuant to amended and restated management agreements between the Adviser, the Funds and the respective general partners of the Funds, has complete and unlimited discretion and authority with respect to the Funds' investments and voting power over investments.

Proxy Voting:

10. Name of the proxy holder:

N/A

11. Number of voting rights proxy holder will ceaseto hold:

N/A

12. Date on which proxy holder will cease to holdvoting rights:

N/A

13. Additional information:

N/A

14. Contact name:

Alexandra A. Toohey, Chief Financial Officer

15. Contact telephone number:

+1-212-339-5690