that the purpose of Prime Minister's Questions was for the House to question the Prime Minister on the actions of the government. This caused such dissent amongst MPs that Martin threatened to suspend the session. Cameron re-worded the question to ask about Blair's future as prime minister rather than leader of the Labour Party, which Martin allowed. Conservative MPs threatened to walk out if a similar event occurred in the future. Personal expenses In 2007, Martin used public money to employ lawyers in challenging negative press stories; media law firm Carter-Ruck was engaged for three months at a cost of more than £20,000. The Liberal Democrat MP Norman Baker criticised the use of taxpayers' money as a "very expensive" way to issue press releases; the Taxpayers' Alliance also expressed disapproval. Martin was also criticised at the same time for trying to block the publication of details of MPs' £5 million-a-year travel expenses under the Freedom of Information Act. On 24 February 2008, John Lyon, the Parliamentary Commissioner for Standards, was asked by the Taxpayers' Alliance to investigate whether Martin had abused parliamentary expenses and allowances. Lyon was obliged to examine all such complaints although the Commissioner could have ruled that the complaint was unfounded. This followed a week in which Martin's spokesman, the veteran Whitehall communications chief Mike Granatt of PR agency Luther Pendragon, resigned after admitting that he had unwittingly misled The Mail on Sunday over more than £4,000 in taxi expenses incurred by the Speaker's wife, Mary Martin. Granatt blamed unnamed officials, but not the Speaker, for falsely informing him that the expenses were legitimate because Martin's wife had been accompanied by an official on shopping trips to buy food for receptions. In fact, her housekeeper had accompanied her; catering for such receptions is the responsibility of the parliamentary caterers. On 29 March 2008, The Daily Telegraph revealed that refurbishment of Michael Martin's official residence, Speaker's House, had amounted to £1.7 million over seven years. The house is inside the Palace of Westminster. On 14 May 2009, The Daily Telegraph reported that Martin had claimed £1,400 for using chauffeur-driven cars that included visits to Celtic Park, home of Celtic Football Club, and his local Job Centre. Damian Green affair In November 2008, Conservative immigration spokesman Damian Green was arrested, in connection with a police investigation into alleged leaks from the Home Office. The MP was detained for nine