Parliamentarians are gathering to pay tribute to the late Baroness Thatcher ahead of the former Prime Minister's funeral next week.

The Commons will debate a motion in the name of Prime Minister David Cameron as MPs are recalled early from their Easter break.

The single line motion will invite MPs to agree they have "considered the matter of tributes to the Rt Hon Baroness Thatcher of Kesteven LG OM". A vote on such a motion would be highly unusual. Debates in the Commons will be allowed to continue until 10pm and MPs who have applied to speak will be called by the chair.

Labour leader Ed Miliband is expected to follow the Prime Minister and Liberal Democrat leader and Deputy Prime Minister Nick Clegg will also make a speech. Tributes will also be paid by peers in the Lords, which has also been recalled early. Former members of Lady Thatcher's cabinets are expected to contribute.

The potential seven-and-a-half-hour length of the Commons debate is itself unorthodox - typically around an hour is spent to mark the death of a former Prime Minister. When Edward Heath died in July 2005, MPs spent 63 minutes paying tributes.

The debates in Parliament come ahead of next week's funeral, the plans for which are being carried out under an operation dubbed True Blue. The Queen and Duke of Edinburgh will attend, Buckingham Palace confirmed yesterday, raising the profile further of the ceremonial funeral, which will have full military honours, at St Paul's Cathedral.

Downing Street is expected to begin releasing details of the guest list, amid speculation that it could include former Soviet leader Mikhail Gorbachev and ex-US first lady Nancy Reagan.

Cabinet Office minister Francis Maude said: "There is already a huge amount of interest, there's a guest list. People will be invited over the coming days." Asked about the Queen's attendance, he added: "I think it's very significant that Her Majesty and the Duke wish to attend. She was a very long-standing prime minister and she was transformational for Britain and also made a huge difference for the world."

Foreign Secretary William Hague has defended the taxpayer contribution to the funeral of Lady Thatcher and the costs of today's debate. He said Britain could "afford" to cover some of the costs of next week's events. Speaking on BBC One's Breakfast programme, Mr Hague said: "It's right Parliament meets and commemorates such a leader of historic proportions in our country's history. She changed the course of our history and there have been many comments over the last few days from all corners of the political spectrum."

Lady Thatcher's family is also meeting an unspecified amount of the funeral cost. Mr Hague said he believed many people on the left's biggest problem with Lady Thatcher was "they could never beat her". "They claimed to stand for millions of people but they could never get as many votes as Mrs Thatcher in an election," he said.