Live blogging | No kiss, just a handshake | Brown's first speech

Gordon Brown promised Britain a "new Government with new priorities" when he became Prime Minister this afternoon.

Arriving in Downing Street after accepting the Queen's invitation to form a Government, the man who has stood in the shadow of Tony Blair for 13 years, first in reforming the Labour party, then in office, said that he would bring change to the country and invite talented people from across the political divide to help him.

"Now let the work of change begin," said Mr Brown.

The focus of national attention finally fell squarely on Mr Brown, who, at 56, is two years older than Mr Blair, when he emerged from Buckingham Palace just before three o'clock this afternoon as Britain's 52nd Prime Minister.

Five minutes later, he climbed out of the Prime Minister's armour-plated car with his wife, Sarah, and spoke his first words to the British public as their leader.

"I have just accepted the invitation of Her Majesty the Queen to form a Government," he said. "This will be a new Government with new priorities and I have been privileged to have been granted the great opportunity to serve my country."

"At all time I will be strong in purpose, steadfast in will and resolute in action in the service of what matters most to the British people: meeting the concerns and aspirations of the whole country... I want the best of chances for everyone, that is my mission."

He then repeated the motto of his old school, Kircaldy High School — "I will try my utmost" — although in its English translation rather than the original Latin 'Usque conabor'.

Mr Brown had left the Treasury as Chancellor of the Exchequer to applause from his staff just minutes after Mr Blair formally offered his resignation to the Queen.

He arrived at the palace at 1:50pm in a scarlet Vauxhall Omega and came out almost an hour later, having accepted the reins of office, to head for No 10.

An afternoon of telephone calls from foreign leaders awaits Mr Brown, whose first acts as Prime Minister are expected within hours as he reshuffles the Cabinet and redistributes the great offices of state. Alistair Darling, the Transport Secretary, is expected to be named Mr Brown's successor at the Treasury as early as this evening.

For the moment — and for the first time in ten years and 57 days — Mr Blair is out of the picture.

The man who woke up as Britain's leader offered his resignation to the Queen shortly after arriving at Buckingham Palace at 1:15pm today and emerged twenty-five minutes later, for the rest of the day at least, with no office to go to.

Britain, briefly, slid into a moment of constitutional limbo, with Sir Gus O'Donnell, the Cabinet Secretary, nominally in charge until Mr Brown's appointment with the Queen saw power transferred to his hands.

Mr Blair's final, five-minute drive as Prime Minister took place after he was clapped out of a packed House of Commons at the end of a final, theatrical appearance at Prime Minister's Questions.

In a session that saw him occasionally close to tears, Mr Blair spoke of the military interventions that will always be associated with his premiership, saying he was "truly sorry" for the dangers British troops face in Afghanistan and Iraq. But he nevertheless defended the decision to send them into battle, claiming that they were fighting for "security in this country and in the wider world".

Following tributes by the Conservative leader David Cameron, Sir Menzies Campbell for the Liberal Democrats and praise from the Rev. Ian Paisley, Mr Blair went on to praise his colleagues in the House of Commons, saying that he had never felt complacent in the chamber.

"From first to last I never stopped fearing it and that tingling apprehension that I felt at three minutes to twelve today I felt as much 10 years ago and every bit as acute," he said. "It is in that fear that the respect is contained."

He added: "The second thing I would like to say is about politics, and to all my colleagues from different political parties: some may belittle politics but we know, who are engaged in it, that it is where people stand tall and although I know it has its many harsh contentions it is still the arena that sets the heart beating a little faster.

"And if it is on occasions the place of low skulduggery, it is more often the place for the pursuit of noble causes. And I wish everyone, friend and foe, well, and that is that. The end."

In a notable break with parliamentary protocol, in which MPs usually shout "Hear Hear" to mark their approval, MPs on both sides of the House stood up and applauded and cheered Mr Blair as he left the arena — the Tories encouraged by Mr Cameron to join in.

Mr Blair's family, including his 7-year-old son Leo, were in the Commons to see his farewell appearance. Beside him on the front bench was a relaxed Mr Brown.

During the session, both Mr Blair and his colleagues appeared demob happy. He changed his formal introduction to the Speaker — in which he traditionally details his future meetings — by saying, to laughter: "I will have no such further meetings later today, or any other day, or ever again."

He also responded to one complex question about the Church of England by Richard Younger-Ross, a Liberal Democrat, by reprising the Catherine Tate catchphrase that he deployed during the recent Comic Relief telethon. "I think I'm really not bothered about that one", he said, before sitting down.

A striking tribute came from Mr Paisley, the Democratic Unionist Party leader and Northern Ireland's new First Minister in its restored power-sharing government.

Referring to Mr Blair’s new job as Middle East peace envoy, Mr Paisley said: "I just want to say to the Prime Minister this one word: he has entered into another colossal task. I hope that what happened in Northern Ireland will be repeated and at the end of the day he will be able to look back and say it was well worthwhile."

After the midday session, Mr Blair returned to his official residence for the last time to hold a farewell drinks reception with his staff.

Within hours of standing down as Prime Minister today, it was announced that Mr Blair had been appointed - by Mr Brown, who is yet to resign as Chancellor despite becoming Prime Minister - as "Steward and Bailiff of Three Hundreds of Chiltern", a legal fiction allowing him to resign from Parliament. At the time Mr Blair was on his way to his Sedgefield constituency, where he was to confirm his departure, prompting a by-election late in July in one of Labour's safest seats.

Times Recommends

• How I lost the gift of joy for a while
• Why Ann Widdecombe has got it wrong
• Alas, it’s the end of the road for petrolheads