"Securing our future for the future". Cameron's incomprehensible promise summed up the failure to meaningfully address Britain's foreign and security policy on yesterday's TV debate, intended to be on "international affairs".

The opening addresses quickly revealed the naivety of anyone who expected a meaningful discussion of foreign policy; the “leaders” clearly believe that the public have no appetite for the discussion of foreign policy, even though Iraq brought more people on to the street than any issue before or since. They are drawing on a long-established tradition, known as the Almond-Lippmann consensus; one that sees popular interest as a volatile, irrational influence on foreign policy which is best ignored.

Hidden within the self-recommendation were the following scant addresses of foreign policy issues

Brown outlined the challenges he thought we faced:

bringing our brave troops safely home from Afghanistan, keeping our streets free of terrorism, building alliances in Europe against nuclear weapons, against climate change, against poverty and to deal with our banks

He said we need to get the big decisions right. But his opening address did not contain a single policy stance; the “big decisions” were not set out, let alone answered. Unless you were under the impression that he didn’t recognise these challenges, this was not enlightening stuff.

Cameron’s call did little to open up the debate:

I want to keep our defences strong, I want to keep our borders secure and our country safe

Clegg’s opener was by far the most meaningful; there were hints of policy, not just the platitudes expressed by Cameron and Brown. Much of this was backward-looking, as is inevitable when opposition to Iraq remains the biggest cup in the Lib Dem trophy-case.

We shouldn’t have sent soldiers in to battle without the right equipment, we shouldn’t be facing allegations of complicity in torture. We shouldn’t have invaded Iraq. So I want us to lead in the world, I want us to lead in Europe, not complain from the sidelines, I want us to lead in creating a world free of nuclear weapons and I want us to lead on the biggest challenge of all – climate change

He made an internationalist pitch, claiming that Britain under the Lib Dems would be a "force for good in the world". Brown did this to a degree, setting out global challenges like climate change and poverty but Cameron, surprisingly, did not mention climate change, framing his arguments firmly within the confines of a narrowly defined national interest.

It was Clegg who took on the mantle of what was in 1997 a radical New Labour demand, laughable though it seems now, that foreign policy “must have an ethical dimension”.

There were four questions in the forty-five minutes purporting to cover international affairs. The first was on Europe and I am not going to talk about it. Europe is no longer a foreign policy issue. The EU is more than that; it affects our laws, industrial relations, consumer rights and economy and is therefore a question of government. A debate on how to forge a European common foreign policy would have been more relevant but the concern of the three, aside from a Cameron attack on Clegg for a proposal to amalgamate the French and British seats on the security council (which wasn’t answered) was insular; the EU’s effect on the UK rather than the UK’s effect on the EU or the EU's effect on the world.

The green question was framed so personally as to postpone any serious discussion:

Given that climate change is one of the biggest global threats we face, what have you personally done in the last six months to use more environmentally friendly and sustainable forms of transport, such as bikes and trains, rather than cars and planes.

“I've been on trains all the time”, said Brown. Cameron told an anecdote about how a critic once asked him, "if you're so concerned about carbon emissions why don't you just stop breathing?” that got a jeer from the labour contingent in the pub where I was watching the debate.

Cameron said he had extra insulation done at his house [I wonder if wisteria clad walls help keep the heat in?] And, should the tories win, you can look forward to getting your own subsidised insulation installed by Marks & Spencers. They do make very good thermal underwear.

Foreign policy then got a flicker of attention after Clegg called for global action on climate change, which then brought the three back into a tussle on Europe and America. Clegg was attacked as anti-American, Cameron as anti-European, with Brown presumably maintaining Blair’s strategic elevation of Britain as a bridge between the US and the EU. Reasonably enough, Clegg claimed “we shouldn’t always do what our American friends tell us to do”, but this did not develop, as it could have, into a debate on Britain's role in the world.

The legacy of Iraq was the undertone here. Clegg was probably wise not to be too triumphant seeing as so many voters were duped. The result was that, overall, the weight of Iraq did more to suppress the debate than enliven it. The leaders’ responses contained none of the grand plans of the Blair years, no kaleidoscopes in flux or missionary zeal. National interest and the domestic impact of foreign policy dominated, and internationalism was marginalised.

Amid Europe, carbon footprints, and the Pope’s state-visit, one well-phrased question gave the leaders an opportunity to address Britain’s role abroad head-on:

Given our involvement in Afghanistan, if there is another multinational operation to remove Al-Qaeda or another terrorist group from a failed state, would the UK participate?

Thank you Stuart Wolvin from Horfield. If you by some chance you read this, I would like to hear what you thought of the responses [a weakness of the format of the debate was the disregard of the questioner once they had read their question, which you at least get a little of on Question Time]

Nick Clegg interpreted the question as “why are we in Afghanistan?”, which is more likely what all the leaders had been preparing for. The answer, "to keep us safe", was hardly satisfactory. The qualifier, "let's make sure we've got the right equipment, the right strategy", was moot.

Cameron got out his little book of anecdotes and told us how "actually, to prepare for this debate, I went for a run this morning with someone who just got back from Afghanistan."

The majority of British voters want troops out within a year. They see, most likely, that Britain’s presence in Afghanistan doesn’t leave us with safer streets. Brown’s argument, a desperate attempt to turn his position as incumbent into an advantage, that the number of intelligence reports he gets of planned attacks emanating from ‘the Aghanistan/Pakistan area’ warrant the occupation is absurd and self-effacing. For one, Britain’s connection with Pakistan is much more significant and it’s most likely that Pakistanis and British citizens with a Pakistani background are far more frequently included in the reports that end up on Brown’s desk “sometimes every day”. But we aren’t occupying Pakistan and Brown knows about them thanks to the security services operating in Pakistan, Afghanistan and the UK, not thanks to an army that has wholly different objectives and concerns.

The debate on Afghanistan was stifled by the leaders’ determination to meet the patriotism threshold. After the first round of answers, Brown broke the seal, and then it was up to Cameron and Clegg to match his praise. The Lib Dem’s are still constrained by the belief that they cannot question the mission when there are troops in the field. It’s another anchor weighing down any public debate on foreign policy.

Brown brought in Somalia and Yemen. His message was stern, warning that "we cannot allow terrorists to have territory in the world that then they use as a base for attacking the United Kingdom". While camps may provide locations for indoctrination and training, the defining feature of terrorism is its extra-territoriality; a bedsit is territory enough to prepare a terrorist plot, a small business could provide sufficient revenue.

The second major foreign policy issue to be addressed, though not the topic of a question, was Trident. This has been widely perceived to be the Lib Dems’ fatal flaw. Ever since Foot ran on a manifesto dubbed the “longest suicide note in history” (many points of which are now in law and accepted Labour party policy), unilateral disarmament has been seen as an election-looser. Cameron sensed the issue slipping from the agenda and “decided to take up this point about Trident”, smelling blood.

But, like Afghanistan, recent polls have shown Trident to be unpopular. Judging by the polls today, the Lib Dems have emerged unscathed and still electable after their derided positions on Europe, immigration and now Trident have been exposed. Last year, 54 percent of people polled wanted to see it scrapped. When they consider these figures, one expects the Conservatives and the Labour leadership call in an Almond-Lippmann defence.

The Lib Dems’ weakness was the uncertainty with which they opposed Trident. Clegg’s case against Trident was not as strong as it could have been, perhaps because having failed to set out an alternative, he was wary to commit to arguments that might later be wheeled out against his own proposals. He was right though to cite Obama, who still has the appeal of a holy text, on the threat of a dirty bomb, and the futility of a deterrent in such a situation. The appeal of joining Obama's bandwagon and soaking up some of his Nobel aura might sway even Brown or Cameron to make a concession on Britain's nuclear arsenal come the Non Proliferation Treaty review in May.

And then came Brown’s barrage; “I say to you, Nick, get real, get real”. Would Clegg survive Brown’s decapitation-strike?

In the pub, the Labour crowd cheered – it was Brown’s big hit. Once the applause had petered out, I turned to a Labour councillor and asked her if she agreed with committing to replace Trident. She wasn’t sure. It was a damning indictment of the tribalism of party politics, and I doubt she was the only one cheering on policies without a thought for what they were.

Throughout, the Labour crowd had cheered Brown’s punch-lines, scoffed at Clegg and Cameron when they fluffed their lines, and even chastised their own leader when he went off course; “look into the camera! Look into the camera!” I behave the same way watching Arsenal, but this isn’t a game; the government is sending people to kill and be killed. You could condense the smatterings of actual debate on foreign policy into ten minutes, probably less. The TV debates have been applauded as “good for democracy”, but however much you appreciate their impact on the polls, we aren’t any closer to having the debate we need on Britain’s role in the world.