John Healey’s shock resignation as Defence Secretary has exposed the bitter conflict at the heart of Government over what many believe is the top priority of any prime minister – keeping the country safe.

Within minutes of him quitting over a lack of funding to ready Britain for war, the anger at Rachel Reeves’s Treasury was palpable, with one Government minister describing her department as a “disgrace”.

Another Whitehall source put it more starkly, telling The i Paper that the Treasury was a “danger” to national security.

The first public signs that the normally loyal Healey was on the brink of resignation came on Wednesday afternoon, under the gilded cherubs of Lancaster House’s state drawing room.

Until then, the Cabinet minister had presented to the world a united front with Sir Keir Starmer, who was tonight scrambling to fill his post following another damaging resignation from his top team.