This week’s ICM poll by the Guardian shows 54% of the public now oppose the renewal of Trident – a marked change from just three years ago when 51% favoured renewal and just 39% opposed it. At the time, the government won House of Commons support for the renewal of Trident with the help of Conservative support.

The erosion in public support for the renewal of an independent nuclear deterrent comes at the same time as public support for military operations in Afghanistan increases. This split decision by the public shows an electorate more willing to prioritise Britain’s military needs than its government.

With a price tag of at least £20bn, the renewal of Trident represents a remarkable expenditure for a weapon of remarkably limited utility. At a time when President Obama is leading calls for a new wave of nuclear weapons reductions, any realistic scenario in which Britain would need to launch a nuclear strike independent of its French and American allies becomes almost unimaginable.

Defence spending has long been a perilous issue in Labour party politics, all the way through from the resignation of Aneurin Bevan over the introduction of charges in the NHS to pay for Korean War rearmament to the call for unilateral nuclear disarmament in the 1983 manifesto – the infamous “longest suicide note in history”.

But good politicians know that precedent only carries you so far, and that adaption is the key to survival in changed circumstances. Whereas the public once viewed a nuclear arsenal as a cornerstone of Britain’s international heft, now the public is more likely to determine the efficacy of British military power by the actual use of conventional force rather than the hypothetical use of nuclear force.

The ability for such a bold break with the past is further enhanced by the support for, at a minimum, serious consideration of non-renewal by such respected defence authorities as former Defence Staff Chief Lord Guthrie, former NATO Secretary General Lord Robertson and former Liberal Democrat Leader Lord Ashdown. Indeed, even the former Conservative Defence Secretary, Michael Portillo, has argued that money spent on renewing Trident would be better spent on conventional defence.

It would be unfair for the public to accuse the government of prioritising resources for a possible future nuclear war over a current conventional conflict – after all, defence procurement is matter of billions of pounds spread over years and years. However, symbolism in both war and politics matters deeply. A reprioritisation from nuclear to conventional defence requirements is vital as a signal of British will to fight and win not only the war in Afghanistan but the probable counter-insurgencies, humanitarian interventions and conventional wars we are likely to face in coming years and decades.

The British public realise this. The defence establishment increasingly accepts this. It is time for the government to act accordingly.