Cameron 'unsure of government's form' as he met Queen
David Cameron has revealed he was not "totally sure" what sort of government he would lead when he met the Queen to become prime minister.
Talks between the Tories and Lib Dems were ongoing and he could only tell the Queen he "hoped to form a coalition".
Mr Cameron added that, on the day before entering Downing Street, he had told his wife Samantha he was sure he would not become prime minister.
The revelations come in a documentary by BBC political editor Nick Robinson.
It looks at the five days of negotiations and deal-making between the three main political parties following the hung parliament delivered by voters in May's general election.
In Five Days That Changed Britain, Mr Cameron says he was "surprised" when then Labour leader and prime minister Gordon Brown decided to leave Downing Street.
He tells Nick Robinson: "I remember having to ring Samantha... and she was doing [daughter] Nancy's homework and I said 'We could be going to the Palace you'd better get your... frock on."
Mr Cameron adds: "I went to see Her Majesty and she asked me to form a government and I said I couldn't be totally sure about what sort of government I was going to form.
"I said that I hoped to form a coalition government but I might have to come back in the morning and tell her it was something rather different."
The Liberal Democrats held talks with the Conservatives and Labour before an agreement was eventually reached with the Conservatives.
Mr Brown faced criticism for staying in Downing Street for several days, despite Labour losing more than 90 seats and coming second to the Conservatives.
Former Business Secretary Lord Mandelson, who led negotiations with the Lib Dems for Labour, told the programme that during this period, the Queen's principal private secretary told him Mr Brown had a constitutional duty to remain in place until a new government could be formed.
Lord Mandelson said he responded by saying there was a "need to bring this thing to as swift and dignified a conclusion as we can".
Meanwhile, former Lib Dem leader Sir Menzies Campbell reveals there is "enormous chemistry" between his successor - and coalition Deputy Prime Minister - Nick Clegg and Mr Cameron.
But he warns: "If you have a dog... for long enough, eventually you begin to look like your pet.
"Well, if you have a coalition partner, then it seems to me there's a very grave risk eventually you'll come to look like them."