Former Conservative party leader and Kent MP Michael Howard is to join a cross-party panel investigating the police raid on the Commons’ office of Ashford MP Damian Green.

The inquiry will be chaired by former Lib Dem leader Sir Menzies Campbell and will scrutinise how the Commons authorities deal with search requests from the police.

The cross-party panel also includes former home secretaries David Blunkett and and ex-foreign secretary Sir Malcolm Rifkind.

Mr Green recently criticized the delay in setting up the panel of inquiry, saying it was disgraceful.

Commons leader Harriet Harman has asked the panel to report by the end of the year.

Mr Green was arrested last year as part of a probe into Home Office leaks but was told in April there would be no charges.

The row that followed led, in part, to former Speaker Michael Martin being forced to quit amid MPs’ criticism for allowing the police to search the MP’s office without a warrant.

The committee will consider if the search broke the rules of Parliamentary privilege.