Cookson Group plc : Holding(s) in Company

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: Ignis Investment Services Limited

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

5. Date of the transaction (and date on which the threshold is crossed or reached if different): 20th January 2012

6. Date on which issuer notified: 23rd January 2012

7. Threshold(s) that is/are crossed or reached: 5%

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
Ordinary Shares B3WK547	Number of shares Not disclosed	Number of voting Rights Not disclosed

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
Ordinary Shares B3WK547		Direct	Indirect 13,752,762	Direct	Indirect 4.97%

B: Qualifying 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

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financial instrument	Exercise price	Expiration date	Exercise/Conversion period	Number of voting rights instrument refers to	% of voting rights
					Nominal	Delta

Total (A+B+C)

Number of voting rights	% of voting rights
13,752,762	4.97%

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

Vidacos Nominees Limited 12,665,533 Ordinary Shares

BNY (OCS) Nominees Ltd 1,087,229 Ordinary Shares

Phoenix Group Holdings

Impala Holdings Limited

Ignis Asset Management Ltd

Ignis Investment Services Ltd (indirect)

Proxy Voting:

10. Name of the proxy holder:

11. Number of voting rights proxy holder will cease to hold:

12.

13. Additional information:

14. Contact name:

RACHEL FELL, DEPUTY SECRETARY, COOKSON GROUP PLC

15. Contact telephone number:

+ 44 (0)20 7822 0000