BBC News Channel

The idea that Theresa May had been forced to make Gavin Williamson defence secretary to shore up her "weak" position was "strictly for the birds", Tory MP Nadim Zahawi has said.

He said the prime minister had shown "real strength" in appointing Mr Williamson, who he described as a "hugely talented" minister who would effectively "champion the cause of the Ministry of Defence".

Hitting back at criticism that Mr Williamson lacked military experience, he pointed out that his predecessor as defence secretary Sir Michael Fallon "didn't have a defence background" when he was given the job.

BBC News Channel

Lord Dannatt - head of the British army from 2006 to 2009 - has cast doubt on whether the new defence secretary has enough experience to handle his complex role.

He described Gavin Williamson as "essentially a political appointment" aimed at shoring up Theresa May's position within the cabinet and although he was a "crafty" operator on the "political battlefield" he had a lot to learn about the military battlefield.

He said it was a "tragedy" that Sir Michael Fallon felt he had to resign and although he wished Mr Williamson well he faced a tough task to master his new brief.

Jonathan Beale
BBC defence correspondent

Gavin Williamson has no military background and has never been a Secretary of State. But he is youthful, a rising star and trusted by Number 10.

He arrives at the Ministry of Defence at a difficult time. His first challenge will be to try to stave off more defence cuts.

The Cabinet Office is currently carrying out a Defence and Security Review which is due to report by the end of the year.

All three services have been asked to put forward options for cuts.

Though there has been a modest rise in the MOD's budget, it’s still got to make more than £20bn of efficiency savings.

There's also pressure to fund an increase in the pay for the armed forces.

They've been struggling with both recruitment and retention. That also hasn't been helped by a political reluctance to put troops in harm's way - something they train for.

There is still unfinished business against so-called Islamic State and Gavin Williamson will be the man who now oversees the RAF air strikes.

Few inside the military or the MOD will know much about him - even fewer on the international stage.

Defence Secretary Gavin Williamson declined to answer questions as he arrived at the Ministry of Defence in Whitehall to begin his new job.

He shook hands with the department's chief civil servant before entering the building.

The BBC's Norman Smith said that as an MP without a military background he faced a "steep learning curve".

Image source, Conservative Party

A previously low profile figure, Julian Smith now has one of the toughest jobs at Westminster, maintaining discipline amid ongoing allegations about sexual misconduct - all at a time when the government is tackling Brexit while lacking a majority of MPs.

The Scottish-born MP for Skipton and Rippon, in North Yorkshire was educated at a comprehensive school, then won a scholarship at a private school for sixth form.

The 46-year-old studied English & History at Birmingham University and became an MP in 2010.

Like Gavin Williamson, he is an ally of Prime Minister Theresa May, and was one of six MPs who led her leadership campaign effort in Parliament.

Image source, PA

The 50-year-old former GMTV presenter was a rising star in David Cameron's government, when she was made employment minister.

But she suffered a setback when she lost her Wirral West seat at the 2015 general election.

However she made a Commons comeback earlier this year, when she was elected MP for Tatton, George Osborne's former constituency in Cheshire.

Tatton MP and former TV presenter Esther McVey is the government's new deputy chief whip, Downing Street has announced.

Deputy chief whip Julian Smith has been promoted to chief whip to replace Gavin Williamson, Downing Street has announced