Labour's postwar history is inescapably linked with the nuclear deterrent.If it weren't for Labour, Britain wouldn't have the Bomb. But it is Labour, more than any other party, that has been split and disfigured by battles over the deterrent.

It was Attlee’s government, in 1946, that took the decision to make Britain a nuclear power at all. The cost – coupled with the wounds of war, and a programme of tight fiscal retrenchment – meant that the two economic ministers, Hugh Dalton at the Treasury and Stafford Cripps at the Board of Trade – now BIS – both believed the cost was too high, and that Britain simply couldn’t afford it.

Years later, Diane Abbott, Labour’s shadow international development secretary, made a similar argument to me, saying: “If you put the same money into building houses and roads it creates jobs and prosperity, but Trident is just dead money. That is the last thing we need when the world is teetering on the brink of another recession.”

But the intervention of Attlee’s Foreign Secretary, Ernest Bevin, ensured that Britain would become a nuclear power. Bevin, in many ways, is the original on which so many of the Labour right’s politicians are mere echoes of: physically imposing, virulently anti-Communist, and reliant upon his political success for his relationship with the trades union right, then as for much of its history based around the Transport and General Workers Union (TGWU), of which Bevin was not only a former general secretary but one of the founders. It was Bevin who as general secretary of the TGWU forced out the pacifist and leftwinger George Lansbury from the party leadership, and his intervention around the Cabinet table was just as vital to the direction of British foreign policy as his earlier move against Lansbury.

Cutting across Cripps, who was midway through a lengthy disposition on the costs of the deterrent, Bevin roared: “That won’t do at all...we’ve got to have this thing, whatever it costs. We’ve got to have a bloody Union Jack on top of it.”

“I don’t mind for myself,” Bevin, who had just finished a telephone call with his American opposite number, said: “but I don’t want any other Foreign Secretary of this country to be talked to or at by a Secretary of State in the United States as I have just had in my discussions with Mr Byrnes.”

And that was pretty much that, with that inner quartet informing the Cabinet of the decision – Parliament wasn’t involved until 1948, two years into the nuclear programme. Bevin and Attlee believed that Britain’s nuclear capability would keep the United Kingdom in the game. They saw it, in the words that Winston Churchill would use a few years later when he was back in Downing Street, as “the price we pay to sit at the top table”.

Judged on those early conversations, Britain’s nuclear deterrent has been a catastrophic failure. British Foreign Secretaries are “talked to or at by a Secretary of State in the United States” in a manner far more condescending and dismissive than anything endured by Bevin. The United Kingdom no longer sits at the top table or anywhere like it. But its capacity to divide Labour remains just as strong.

Labour went into opposition in 1951, and the party faithful almost immediately decided that it was because the Labour government had been insufficiently leftwing. Internal opposition to Attlee coalesced around Aneurin Bevan - “Nye” for short - who had resigned from the government in its dying days over the programme of rearmament. Attlee and his former ministers were criticised for spending too much on defence in general and the nuclear deterrent in particular.

Splits over defence – with Attlee and his eventual successor, Hugh Gaitskell, on one side, and Bevan and his followers on the other – scarred Labour’s years in the wilderness. Writing in 1989, Denis Healey reflected:

“We use to describe the period of Conservative Government from 1951 to 1964 as ‘thirteen wasted years’. The first eleven of those years were wasted by the Labour Party. Our bitter internal wrangling at the time gave us a reputation for division and extremism from which we have not yet recovered.”

But by 1964, with both Bevan and Gaitskell dead, Labour returned to power – and its first major division was on the issue of whether to scrap the Polaris nuclear submarines, the predecessor to Trident.

Just as in 1946, the new Labour government had the opportunity to kill off Britain’s nuclear programme. Harold Wilson, the Prime Minister, colluded with Denis Healey – a Bevinesque bruiser from the party’s right, then at Defence – telling him to tell the Cabinet that the programme was already too advanced to be mothballed. (In reality, the new government could easily have cancelled the submarines. Healey recalled the Cabinet meeting that followed:

“Jim [Callaghan, the Chancellor of the Exchequer] wanted it down to three, just to save money, of course. But George Brown wanted it down to three on the grounds that with three boats we couldn’t be sure of always having one on patrol, and therefore it couldn’t be regarded as capable of being used independently. I remember Michael Stewart saying at the time that it reminded him very much of when he was on the committee of the Fulham Co-op in the 1930s and they were discussing, being good Methodists all, whether, for the first time, they should stock wine. And they finally decided they would stock wine, but only very poor wine.”

In many ways, Polaris – and Trident, the like-for-like replacement which came in 1996 – is the “very poor wine” of nuclear deterrence. By 1964, the Attlee government’s ambitions that Britain could maintain “Great Power” status had been shattered. Hopes of a ground-to-air nuclear missile, or a bomber fleet had both been scrapped, while instead of building its own deterrent, the missiles themselves were bought “off the shelf” from the United States. (The submarines are made in Barrow, however.) The United Kingdom is a nuclear state – but only just - .

Poor wine drank in large amounts can still cause family feuds, and the deterrent still retains its capacity to split Labour, not just during its period of opposition in the 1980s but even in the New Labour years. 95 Labour MPs, including Charles Clarke, the former Home Secretary, rebelled over Trident in 2007. Stephen Pound resigned from the government to vote against Trident, although he returned to the frontbench a year later and is still there now. This latest bout of in-fighting, in many ways, is just a case of history repeating

Whether the nuclear issue will remain as potent an electoral asset for the Conservatives as it was in the 1980s remains up for debate – but just as it has throughout the party’s history, the Bomb has lost none of its power to divide Labour.