Holding(s) in Company

Cookson Group PLC
30 January 2007



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             2,235,737*
     Chase GA Group Nominees Limited                5,112,473*
     Chase Nominees Limited                           360,267*
     CUIM Nominee Limited                           1,884,816*
     Chase Nominees Limited                           412,822
     CUIM Nominee Limited                             205,821
     Vidacos Nominees Limited                          62,955


     * denotes direct interest



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

25 JANUARY 2007



6. Date on which issuer notified:

29 JANUARY 2007



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

5% to 4% change at direct interest level



8. Notified details:

.................





A: Voting rights attached to shares


Class/type of shares if possible              Situation previous to the Triggering transaction
using the ISIN CODE
                                  Number of shares                   Number of voting Rights


Ordinary Shares

GB00B07V4P80                      9,746,574                          9,746,574





Resulting situation after the triggering transaction


Class/type of shares if      Number of shares         Number of voting rights           % of voting rights
possible using the ISIN CODE
                             Direct                   Direct       Indirect             Direct      Indirect


Ordinary Shares

GB00B07V4P80                 9,593,293                9,593,293    681,598              4.96        0.35



B: Financial Instruments

Resulting situation after the triggering transaction


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

                                                      N/A





Total (A+B)
Number of voting rights        % of voting rights


10,274,891                     5.31



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

See Section 4



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:

Figures are based on a total number of voting rights of 193,357,175.



14. Contact name:

RACHEL FELL, DEPUTY SECRETARY, COOKSON GROUP PLC



15. Contact telephone number:

020 7822 0000




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