'Unprepared' Britain faces '1936 moment' warn defence heavyweights in urgent appeal to Keir Starmer

They have insisted Britain is unprepared for military conflict with Russia - and must urgently re-arm.

Signees of the letter include former Defence Secretary Sir Ben Wallace, ex-National Security Advisor Lord Darroch and Professor Anthony King, a leading defence expert.

The letter reads: "Britain lacks the mass, readiness and resilience needed to produce a credible deterrent in an era of intensifying threats.

"Britain's actions fall dangerously short of matching our rhetoric and our meeting of Nato treaty obligations. We are deluding ourselves if we believe Russia and our other adversaries are unaware of this.

"With defence spending at 2.4 per cent and a longer-term Nato goal of 3.5 per cent is simply not enough to rebuild mass, close funding gaps and get our Armed Forces into a state of readiness."

The letter was drafted by the Defence on the Brink podcast team and signed by former chair of the Commons Defence Select Committee, Tobias Ellwood, ex-Army chief Lord Dannatt, and ex-MI6 boss Sir Richard Dearlove.

The letter suggested Britain was facing a "1936 moment" - referencing the threat posed by Nazi Germany as Europe teetered on the brink of World War II.

It continued: "You must recognise that we are facing our 1936 moment: global conflict is highly likely if we don't invest in deterrence now."

It comes after repeated postponements to the Defence Investment Plan.

Charles Woodburn, chief executive of BAE Systems, said the plan's delay was holding back investment in the industry.

Sir Keir said earlier this week the Government needs to "go faster" on defence spending in response to reports the MoD was pushing to increase funding to three per cent of GDP by 2029 - five years earlier than planned.

While he has also pledged to meet the Nato obligation of five per cent by 2035, this includes 1.5 per cent on security infrastructure projects such as mending roads, with only 3.5 per cent dedicated towards defence spending.

The letter's signatories have called on the Prime Minister to announce a "bold, credible, and measurable path" to boost defence spending.

They added that public concern about defence is now an equal priority to the NHS and cost of living.

They also said the cost of the Chagos deal, National Insurance for the MoD, and above-average pay rises had eaten up budgets and undermined frontline readiness.

In this financial year, £2billion has been shaved off the defence budget, with Rachel Reeves believed to be opposed to a major increase in spending.

Britain last spent 3.5 per cent of GDP on defence in 1994, with five per cent last being spent in 1986.

A Government spokesman said: "The Prime Minister has made a historic commitment to spend five per cent of GDP on defence and security from 2035. This is a generational increase and we are well on track to meet that target.

"As demands for defence increase, we are delivering the largest sustained increase in defence since the Cold War, with an additional £5billion this financial year and £270billion across this Parliament.

"We make no apologies for delivering the largest pay rise in decades to our hard-working personnel and a £9 billion housing strategy to renew tens of thousands of military homes after years of neglect."