MPs demand inquiry into revelations that Prince Charles sent staff to work in Whitehall The Prince of Wales was accused tonight of an "astonishing" breach of his constitutional role by dispatching employees to work in two Government departments. The disclosure that three members of his staff had been seconded to Whitehall followed last week's revelation that the heir to throne has had 36 private meetings with Cabinet members since the 2010 general election. Demands for 27 letters written by the Prince to ministers in the previous government to be released have also been blocked by the Attorney General. MPs are preparing to challenge ministers over the secondments when Parliament returns next month and will attempt to trigger a Commons inquiry into the Prince's influence over the Government machine. Clarence House confirmed three staff members had been seconded to departments over the past five years.All three were said to be junior personnel who had been given the placements, which ranged from six weeks to two years, to develop their careers. It strongly denied they had been sent there to advance issues close to the Prince's heart. But the Labour MP Paul Flynn said the latest disclosures - the first known secondments from the Royal Household to Whitehall - were the "last straw." He told The Independent: "We now have this extraordinary story that he put his minions in two departments. Few things really surprise me, but I'm astonished by this. His main qualification for the job is that he doesn't get involved in politics. Mr Flynn said he would be pressing to add the issue to the agenda of the Commons political and constitutional reform select committee, of which he is a member. "While we are calling for transparency in lobbying, that principle certainly extends to lobbying by the next in line to the throne," he said. One staff member from Clarence House was seconded to the Cabinet Office for two years and a second spent six weeks in the department, which has oversight of constitutional issues. A third employee spent a year in the Department for the Environment, Food and Rural Affairs, which is responsible for agriculture and GM foods, subjects in which the Prince takes a close interest. It also has responsibility for the planned badger cull, which he supports. An unnamed minister told The Sunday Times the secondments raised fears the Prince was exceeding his position as a constitutional monarch in waiting. There is a question about what they are doing and whether they are influencing policy," the minister said. Paul Farrelly, a Labour MP, said he would ask ministers about the secondments when the Commons comes back after the summer recess. "It raises constitutional questions about the influence the monarch in waiting has over policy and there will be questions in the House when it returns," he said. A Clarence House spokesperson said: "We have had two secondments to government departments in the past two years. The secondments were suggested on the basis of professional development and the paperwork was arranged by the relevant HR departments. One secondment was one year and the other was for two years. Both have come to a natural conclusion. There was no official feedback mechanism and no regular meetings were attended with the Prince of Wales's Household. The secondments were on a like for like basis. One secondee has now left Clarence House and the other is due to return shortly after a sabbatical. Over the past five years, in addition to the two secondments already discussed, there has been one other secondment, for six weeks to the Cabinet Office. We have no new secondments planned at present. Ministers have previously expressed private fears that Prince Charles may interfere too readily in government decisions when he becomes king. The former Downing Street director of communications, Alastair Campbell, wrote in his diaries that Tony Blair was irritated by the Prince's public interventions over sensitive policy areas.