Holding(s) in Company

4th Apr 2007 10:00

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:

JPMORGAN CHASE & CO

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

J.P. MORGAN INVESTMENT MANAGEMENT INC

JPMORGAN ASSET MANAGEMENT (UK) LIMITED

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

2 APRIL 2007

6. Date on which issuer notified:

4 APRIL 2007

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

5% 8. Notified details:¢â‚¬¦¢â‚¬¦¢â‚¬¦¢â‚¬¦¢â‚¬¦..

A: Voting rights attached to shares

Class/type of shares if possible Situation previous to the using the ISIN CODE Triggering transaction Number of Number of voting shares Rights GB00B07V4P80 11,120,525 5.75%

Resulting situation after the triggering transaction

Class/type of shares if possible using Number of Number of voting % of voting the ISIN CODE shares rights rights Direct Direct Indirect Direct Indirect GB00B07V4P80 0 0 Below 5% 0 Below 5% B: Financial Instruments

Resulting situation after the triggering transaction

Type of Expiration Exercise/ Number of voting rights that may be % of financial Date Conversion acquired if the instrument is voting instrument Period/ Date exercised/ converted. rights N/A Total (A+B)Number of voting % of voting rights rights Below 5%

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

Total disclosable holding for JPMorgan Chase & Co: below 5%

Holdings by controlled undertaking of JPMorgan Chase & Co are as follows:

J.P. Morgan Investment Inc

JPMorgan Asset Management (UK) Limited

Proxy Voting:

10. Name of the proxy holder:

N/A

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:

The group has other holdings which are covered by exemptions.

14. Contact name:

RACHEL FELL, DEPUTY SECRETARY, COOKSON GROUP PLC

15. Contact telephone number:

020 7822 0000

COOKSON GROUP PLC

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Related Shares:

Vesuvius