Holding(s) in Company

RNS Number : 6672P

Cookson Group PLC

30 March 2009

TR-1: NOTIFICATION OF MAJOR INTERESTS IN SHARES

1. Identity of the issuer or the underlying issuer of existing shares to which voting rights are attached:

COOKSON GROUP PLC

2. Reason for the notification (please state Yes/No):

An acquisition or disposal of voting rights: ( Yes )

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

An event changing the breakdown of voting rights: ( )

Other (please specify): ( )

3. Full name of person(s) subject to the notification obligation:

Aviva plc & its subsidiaries

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

Registered Holders:

BNY Norwich Union Nominees Limited 63,951,465*

Chase GA Group Nominees Limited 186,614,235*

Chase Nominees Limited 8,448,035*

CUIM Nominee Limited 40,319,337*

Vidacos Nominees Limited 355,368*

Chase Nominees Limited 16,052,745

Vidacos Nominees Limited 1,179,594

* denotes direct interest

5. Date of the transaction (and date on which the threshold is crossed or reached if different):

26 March 2009

6. Date on which issuer notified:

27 March 2009

7. Threshold(s) that is/are crossed or reached:

11% to 10% change at direct interest level

8. Notified details:

A: Voting rights attached to shares

Class/type of shares if possible using the ISIN CODE	Situation previous to the Triggering transaction
	Number of shares	Number of voting Rights
Ordinary Shares GB00B07V4P80	327,106,614		327,106,614

Resulting situation after the triggering transaction

Class/type of shares if possible using the ISIN CODE

Number of shares

Number of voting rights

% of voting rights

Direct

Indirect

Direct

Indirect

Ordinary Shares

GB00B07V4P80

299,688,440

17,232,339

10.84

0.62

B: Financial Instruments

Resulting situation after the triggering transaction

Type of financial instrument	Expiration Date	Exercise/Conversion Period/ Date	Number of voting rights that may be acquired if the instrument is exercised/ converted.	% of voting rights
N/A

Total (A+B)

Number of voting rights	% of voting rights
316,920,779	11.46

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

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 cease to hold:

N/A

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

N/A

13. Additional information:

14. Contact name:

RACHEL FELL, DEPUTY SECRETARY, COOKSON GROUP PLC

15. Contact telephone number:

020 7822 0000