Holding(s) in Company

Radstone Technology PLC
15 May 2006

The Company has received the following notification:



                                              Wellington Management Company, LLP
                                                                 75 State Street
                                                                          Boston
                                                             Massachusetts 02109
                                                       Telephone: [phone]





12 May 2006



N Novakovic
Company Secretary
Radstone Technology plc
Tove Valley Business Park
Towcester
Northamptonshire
NN12 6JN




Notification concerning interests in shares of Radstone Technology plc 
(the "Company")



Dear N. Novakovic:



1

Wellington Management Company, LLP ("Wellington Management") is registered as an
investment adviser with the United States Securities and Exchange Commission
under section 203 of the Investment Advisors Act of 1940, as amended and acts as
discretionary investment manager on behalf of various separate accounts (the 
"Accounts") that hold an interest in shares of the Company. Wellington
Management's interest in the shares is as an investment manager, as is mentioned
in Section 205(5) of the Companies Act 1985 (the "Act"). The Accounts do not act
as a group nor do they act in concert with respect to the interests in shares.
Wellington Management acquired the interests in shares for the Accounts in its
capacity as discretionary investment manager to, and solely for the benefit of,
the Accounts, and the interests were acquired solely for investment purposes.
The shares are registered in the name of the Accounts or the Accounts'
custodians or nominees according to their respective holdings.



2

Wellington Management as discretionary investment manager on behalf of the
Accounts currently holds, in the aggregate, an interest, within the meaning of
Sections 203 and 208 of the Act, in 1,480,518 ordinary shares, or 4.88% of the
shares outstanding of the Company. This represents a decrease of 0.87% since our
last notification on 06 April 2006. Therefore, Wellington Management hereby
gives notice to the Company of such interest in shares, pursuant to the
provisions of Sections 198(1) and 208(4)(B) of the Act.



3

This notice is given in fulfilment of, and for the express purpose of
discharging the obligations imposed on us by, Sections 198(1) and 208(4)(B) of
the Act and arising out of the circumstances referred to in paragraph 2.



If you have any questions or comments, please do not hesitate to contact me at
[phone].



Regards,



Julie A. Jenkins
Vice President and Counsel
Wellington Management Company, LLP




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