Members of the cabinet have gathered for their first meeting, as David Cameron puts the finishing touches to his historic coalition government.

Afterwards, Universities Minister David Willetts said the cabinet was "getting straight down to business".

Education Secretary Michael Gove said there was a "sense of partnership and common purpose".

Later, Mr Cameron will announce a string of junior government posts, including further Lib Dem appointments.

He began the business of government on Wednesday evening with a first meeting of the new National Security Council. It followed a press conference in the No 10 garden with deputy prime minister and coalition partner Nick Clegg.

During the event, the two men joked together as they set out what they wanted to achieve with the first UK coalition government since the second world war - an alliance Mr Cameron said could mark a "seismic shift" in British politics.

In Thursday's first cabinet meeting, Mr Clegg sat opposite Mr Cameron who had Foreign Secretary William Hague sat beside him.

'Wonderful feeling'

In addition to Mr Clegg, four other Lib Dems were at the cabinet table. They were Vince Cable, who is Business Secretary; Chief Secretary to the Treasury David Laws; Energy and Climate Change Secretary Chris Huhne; and Scottish Secretary Danny Alexander.

Mr Cameron told those gathered: "I think we have a great opportunity to think for the long term.

"One of the things that has been a real problem in recent years is the sense there might be a general election - well, I certainly felt it - there might be a general election at any moment, [which] meant that government didn't think for the long term and I think we have a great opportunity to do that."

Mr Cameron talked a lot about Afghanistan and said he "couldn't stress how high it was on the new government's agenda". Defence Secretary Liam Fox said he would be updating parliament much more frequently on the situation in the war zone.

Mr Hague said he was pleased that the government appeared to have been well-received internationally.

The BBC News channel's chief political correspondent Laura Kuenssberg said cabinet members were encouraged to keep their differences quiet and told that a special coalition committee would be set up, co-chaired by Mr Cameron and Mr Clegg, to provide a forum in which to thrash out any disagreements.

She also said the first new rule issued to the cabinet this morning was that members were banned from having their mobile phones and Blackberrys with them during meetings.

Chancellor George Osborne told the meeting that the deficit "overshadows everything" and confirmed that all ministers would take a 5% pay cut.

There was room for some levity, however, with a joke from Mr Cable. He said his Indian in-laws had always told him that arranged marriages were sometimes better than those borne out of love.

Home Secretary

There are expected to be 20 Liberal Democrat ministers at all levels across many departments, meaning more than a third of their 57 MPs will be members of the government.

The majority of cabinet ministers carry on with the briefs they held in opposition but there was a return to frontline politics for former Tory leader Iain Duncan Smith, who becomes work and pensions secretary.

After the meeting, Mr Duncan Smith said it was "a wonderful feeling" to see Mr Cameron in the prime minister's chair. Mr Gove said it was "a really constructive meeting" and it was "great" to be sat alongside his new Liberal Democrat colleagues.

Theresa May was a surprise appointment as Home Secretary and she has already spoken of the challenges ahead as she tries to square the conflicting priorities of the coalition partners and deliver their jointly agreed programme.

She told BBC News: "We will be scrapping ID cards but also introducing an annual cap on the number of migrants coming into the UK from outside the European union."

She said there was a "process to be gone through" to decide the annual limit. The coalition government was committed to introducing elected police commissioners and cutting police paperwork to "give the police more time on the streets," she added.

On the DNA database, she said: "One of the first things we will do is to ensure that all the people who have actually been convicted of a crime and are not present on it are actually on the DNA database.

"The last government did not do that. It focused on retaining the DNA data of people who were innocent."

Health Secretary Andrew Lansley told the BBC the new government would go further than Labour's planned £20bn of health service efficiency savings over the next three years.

"Of course we do need to do that, and we may need to do more because we have increases in demand in the NHS and a need to improve the outcomes. Every penny that is saved by doing things better can be reinvested for the benefit of patients."

Speaking after the cabinet meeting, Culture Secretary Jeremy Hunt said the economy was the top priority, but played down suggestions that there might be shock among cabinet members now they had seen the true state of the country's finances. "We were all aware of the seriousness of the situation," he said.

National Security

One junior government post was revealed on Wednesday evening, when Dame Pauline Neville-Jones took her seat as Security Minister at the first meeting of the National Security Council.

The body, made up of senior ministers, military chiefs and the heads of the security services, discussed the military situation in Afghanistan. It was also briefed on the UK's wider strategic and security position.

The council was set up on Wednesday to co-ordinate the efforts of government departments and agencies to safeguard UK security.

A Downing Street spokesman said: "The prime minister began the meeting by paying a full tribute to the UK's armed forces and expressed his personal admiration and gratitude for their dedication and sacrifice.

"He then received briefings on the political and military situation in Afghanistan, including from his new National Security Adviser, Sir Peter Ricketts, and from the Chief of the Defence Staff [Sir Jock Stirrup]. The prime minister was then updated on the wider UK security situation."

The Labour Party has meanwhile started the process of choosing a new leader after the resignation of Gordon Brown, who stood down as prime minster on Tuesday when it became clear that the Lib Dems had decided to join the Tories in a coalition.

Former Foreign Secretary David Miliband became the first potential candidate to announce plans to stand, saying he hoped others would follow suit. He has the backing of heavyweight figures including former home secretary Alan Johnson and acting Labour leader Harriet Harman, both of whom have ruled themselves out of the running.

Backbench Labour MP John Cruddas, who came third in Labour's 2007 deputy leadership contest, has also said he is thinking about standing.