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

Abcam 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

No

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

No

An event changing the breakdown of voting rights

No

Other (please specify):

No

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

William Blair & Company, L.L.C

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

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

10th September 2012

6. Date on which issuer notified:

11th September 2012

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

Fell below 5% threshhold

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

GB00B6774699

10,114,765

9,981,520

9,796,699

9,671,318

4.87%

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

n/a

n/a

n/a

n/a

n/a

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

n/a

n/a

n/a

n/a

n/a

Nominal

Delta

n/a

n/a

Total (A+B+C)

Number of voting rights

Percentage of voting rights

9,671,318

4.87%

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

William Blair & Company, L.L.C. (William Blair) is an investment adviser registered under the U.S. Investment Advisors Act of 1940. As such, pursuant to advisory contracts, William Blair has the power to purchase and sell securities on behalf of its clients and the power to vote for most clients. Persons other than William Blair are entitled to receive all dividends from, and proceeds from the sale of all securities reported hereunder.

Proxy Voting:

10. Name of the proxy holder:

William Blair & Company, L.L.C.

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:

14. Contact name:

Jeff Iliffe

15. Contact telephone number:

01223 696000