Question to the Home Office:

To ask the Secretary of State for the Home Department, if the Government will place a time limit of 28 days on immigration detention.

The Government has no plans to introduce a fixed time limit on immigration detention as this would only encourage detainees to refuse to cooperate with immigration and asylum processes until they reached the point at which they had to be released from detention and thus avoid their enforced removal from the UK. Published Home Office policy is clear, however, that detention is only used for the shortest period necessary.

https://www.gov.uk/government/publications/offender-management