Defence chief's comments on Jeremy Corbyn show how cuts have loosened military tongues

Sir Nicholas’s assertion is latest in a series of khaki-hued interventions in the political arena by senior military figures

Chief of the Defence Staff, General Sir Nicholas Houghton, who has said that Jeremy Corbyn's stance on nuclear weapons would 'seriously undermine' Britain’s deterrent (PA)

Ever since Montesquieu decided tyranny was best thwarted by separating out the powers of the key organs of state, politicians and generals have trodden warily along the boundary between their respective territories of democracy and defence.

But while the 17th-century French philosopher, who was himself the son of a soldier, was adamant about the need for the strict division of governmental powers, Britain’s military leaders have discovered a recent taste for a spot of constitutional skirmishing.

Chief of the Defence Staff, General Sir Nicholas Houghton’s assertion that Jeremy Corbyn’s stance on the use of nuclear weapons would “seriously undermine” Britain’s deterrent is the latest in a series of khaki-hued interventions in the political arena by senior military figures.

There are no formal laws in Britain which ban serving generals, admiral or air chief marshals from expressing political views but it is a long-held convention that they do not stray far - at least in public - into the realm of the rectitude of the opinions or policies of their political masters.

But years of cuts to budgets and the scrutiny of the political decisions which led to costly interventions in places such as Iraq and Afghanistan seem to have loosened military tongues.

Two years ago, Sir Nicholas put his head over the parapet to warn that cuts to defence spending risked leaving the UK with “hollowed-out” armed forces.

More commonly, the job of criticising those in power falls to retired generals whose only access to weaponry is their golf clubs. Prime Minister David Cameron earlier this year slapped down a group of complaining former top brass by suggesting their criticism was inspired by a desire to sell books.

It is unlikely, however, retired officers would intervene without some degree of tacit approval from their active successors.

For some, such interventions are a necessary and welcome professional insight from those charged with the defence of the realm. But for others, these incursions amount to a disturbing blurring of the distinction between the elected representatives who give the orders and those charged with executing them.