from Hansard:  http://www.publications.parliament.uk/pa/cm200405/cmhansrd/cm041208/text/41208w37.htm#41208w37.html_sbhd5

" Lynne Jones: To ask the Secretary of State for the Home Department with reference to the seizure of servers belonging to Indymedia, what statutes govern the seizure of private property in the UK by foreign law enforcement agencies without authorisation from UK law enforcement agencies. [201718]

Caroline Flint: Foreign law enforcement agencies are permitted to seek the seizure of private property in the UK to secure evidence in connection with a criminal investigation, by sending a request to the UK Central Authority (UKCA) at the Home Office through mutual legal assistance procedures under the Crime (International Co-operation) Act 2003 and the Police and Criminal Evidence Act 1984. The UKCA considers such requests in conjunction with the appropriate UK law enforcement agency. If the request is approved UKCA will then issue a direction to the courts on behalf of the Secretary of State authorising an application for a search warrant.

In this particular case, I understand that, in accordance with a US Commissioner's subpoena, a US based company accessed its servers in London from the US, in order to comply with the terms of that subpoena. No UK law enforcement agencies were involved in this action. "
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Also, despite neither confirming the existance or not of a 'mutual legal assistance treaty', why does the letter state that they are not just for terorism etc?

Especially when Blunkett states that "no prior notification was recieved"
 http://www.publications.parliament.uk/pa/cm200304/cmhansrd/cm041108/text/41108w08.htm#41108w08.html_sbhd1

Can they 'do it' then put a letter in the post, 2nd class, asking for mutual legal assistance?