A former head of the armed forces has warned ministers they must increase spending on defence if Britain is to remain a world military power.

General Lord Houghton said the UK was at a “strategic crossroads” and the Government had to decide what sort of country it wants to be in a post-Brexit world.

He said the current defence programme, as set out in David Cameron’s 2015 Strategic Defence and Security Review, was “wholly unaffordable” based on existing resources.

Gavin Williamson allegations
Defence Secretary Gavin Williamson is reportedly in dispute with the Prime Minister and Chancellor (Dominic Lipinski/PA)

He backed a call by the cross-party Commons Defence Committee for the Government to raise spending on defence from the Nato minimum of 2% of GDP to 3%.

“The Government now finds itself in a very difficult situation,” he told the BBC Radio 4 Today programme.

“It faces this problem at a time when the world is a more dangerous place, when the range of threats is more diverse, but precisely the time when a post-Brexit Britain aspires to rebrand and reassert itself as a global player.”

Lord Houghton, who stood down as the chief of the defence staff in 2016, said the public had been “deluded” into thinking that Britain was set to gain major new military capabilities when the funding was not there to pay for them.

He said the country now needed to decide whether it wanted to provide the necessary resources to maintain its status as a “global Britain” or accept that it was no longer a major military power.

“We are to an extent living a lie.

“We stand at a strategic crossroads. We have got to come off the fence one way or another.

“It might be, and it is a wholly worthy opinion, that the United Kingdom should cease to be a world military power,” he said.

“We stand in a period where, to be honest, our sense of national identity and credibility is wobbling.

“We need to have a strategic decision that flows from government about what sort of a place and a country the UK wants to be going forward.

General Houghton comments
Lord Houghton has warned over the state of the UK Armed Forces (Harland Quarrington/MoD/PA)

“To me that is best served as a global Britain, as a strong military power, as a good alliance member, as a country that will help secure the stability of the world.”

His intervention comes amid reports that Theresa May and Chancellor Philip Hammond have clashed with Defence Secretary Gavin Williamson over the level of military capability the UK needs to maintain.

After the Prime Minister’s promise of £20 billion-a-year extra for the NHS, allies of Mr Williamson on the Tory backbenches are reportedly threatening a revolt if there is no additional funding for defence in the Budget in the autumn.

Lord Houghton said the issue was more important than any political struggle for power.

“To my way of thinking it would be a great shame if future of the defence budget and the armed forces of this country were somehow part of a political game for power and ambition.

“I hope that is not the case.”

Prime Minister Theresa May’s official spokesman said that retired senior officers were “perfectly entitled to contribute to this debate”.

The spokesman pointed to comments by Nato secretary general Jens Stoltenberg during a visit to London last week, in which he hailed the leading role played by the UK in the transatlantic alliance across a wide range of military capabilities.

“We will continue to provide that function,” said the PM’s spokesman.

“We have a commitment to 2% (of annual GDP) funding on defence and a commitment to a 0.5% increase in real terms each year. We have a commitment to spending almost £180 billion on equipment over the next decade.”