Holding(s) in Company

TR-1: NOTIFICATION OF MAJOR INTEREST IN SHARESi

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

Instem plc

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

An acquisition or disposal of voting rights

√

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 thenotification obligation: iii

Aviva plc & its subsidiaries

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

Registered Holder:

BNY Norwich Union Nominees Limited 52,330*

Chase (GA Group) Nominees Limited 292,673*

*denotes direct interest

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

28 February 2013

6. Date on which issuer notified:

01 March 2013

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

3% to

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 SharesGB00B3TQCK30

455,003

455,003

345,003

345,003

Nil

2.93%

Nil

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

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

Percentage of voting rights

345,003

2.93%

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

The voting rights are managed and controlled by Aviva Investors Global Services Limited, with the following chain of controlled undertakings:-

Aviva Investors Global Services Limited:

·; Aviva plc (Parent Company)

·; Aviva Group Holdings Limited (wholly owned subsidiary of Aviva plc)

·; Aviva Investors Holdings Limited (wholly owned subsidiary of Aviva Group Holdings Limited)

·; Aviva Investors Global Services Limited (wholly owned subsidiary of Aviva Investors Holdings Limited)

Proxy Voting:

10. Name of the proxy holder:

See Section 4

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

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

13. Additional information:

Figures are based on a total number of voting rights of 11,764,658 as per the Company's Posting of Annual Report, Notice of AGM Announcement of 8 May 2012. 

14. Contact name:

Neil Whittaker, Aviva plc

15. Contact telephone number:

01603 684420