Holding(s) in Company

Radstone Technology PLC
07 April 2006


The Company has received the following notification:

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


06 April 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 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 has purchased, in the aggregate, an interest, within the meaning of
Sections 203 and 208 of the Act, in 1,741,076 ordinary shares, or 5.75% of the
shares outstanding of the Company. This is a decrease of 0.88% since our
notification on 03 February 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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