In September 2014 the Coalition Government put forward a motion to Parliament asking for its consent to carry out strategic air strikes against the so-called Islamic State in Iraq.

We chose, after much discussion and analysis, not to ask for consent to do so in Syria, despite IS gaining ground on both sides of the border.

That distinction was not trivial: it was based on a clear rationale that our intervention could be effective in Iraq in a way that it couldn’t be in Syria.

But, if you listen, the mood music is changing. The Government is laying the groundwork to launch air strikes in Syria.

Just a few days ago Defence Secretary Michael Fallon said it was “morally wrong” for the UK not to target IS in Syria as well as Iraq, arguing that: “We can’t leave it to French, Australian and American aircraft to keep our own British streets safe.”

Presumably, then, given that we put intervention in Iraq but not Syria to a vote just a year ago, something quite dramatic must have changed?

The distinction between Iraq and Syria was clear. In Iraq, the legitimate domestic government was asking us for assistance; a coalition of Arab countries was prepared to lead that effort; and, crucially, the air strikes could be complemented by a ground offensive led by the Iraqi army.

The Iraqis were fighting IS and asking for our help.

"The impression the Tories seem to give is that they wanted to take military action all along but were thwarted in doing so by the Labour Party" Nick Clegg

Syria, on the other hand, was — and remains — a messy and chaotic civil war between Bashar al-Assad’s brutal regime, IS, the Free Syrian Army and a number of other players. It is a humanitarian disaster, the consequences of which we are seeing on our doorstep as the refugee crisis grows.

David Cameron made this distinction himself in the House of Commons at the time of the vote. Now it seems the Government wants to join the bombing of Syria. Why the shift?

The first reason is the one Fallon suggests: more of our allies are now dropping bombs, so the Government appears to believe we have a duty to join in too. And not just our allies: Vladimir Putin has chosen the cauldron of Syria to flex his muscles, wading in to blow up the enemies of his ally Assad — primarily, it appears, the Free Syrian Army rather than IS.

The second is that David Cameron is now the Prime Minister of a Conservative majority government. The humbling defeat of the last Government in the Commons in 2013 when we proposed to support an American plan to deal with Assad’s chemical weapons grows more distant by the day. Joining in air strikes seems to be viewed in Whitehall as a way of finally drawing a line under that episode.

The third is that the refugee crisis has now reached Britain’s shores, stoking the public demand for something — anything — to be done.

And the fourth is that Jeremy Corbyn, a lifelong anti-war campaigner, has been elected Labour leader, a fact that the Conservatives have not hesitated to exploit.

The impression the Conservatives seem to give is that they wanted to take military action all along but were thwarted in doing so by the Labour Party — or because they didn’t have a majority in Parliament of their own.

This is not true. The decision not to bomb Syria was taken by Cameron and myself and discussed across both sides of the Coalition. The logic was simple: there was no coherent ground campaign in Syria to which air strikes could usefully contribute. While we were, of course, aware of the parliamentary constraints we faced, the overriding reason we did not push for air strikes in Syria was that dropping bombs on a country without a workable military approach on the ground made little strategic sense.

On the substance on which we based our collective decision in 2014, nothing has changed. If anything, the evolving circumstances make air strikes less justified. All there is on the ground in Syria is chaos, blood and anger. We would simply be throwing more bombs into a furnace.

And in the skies we have an increasingly precarious, unpredictable situation as US and Russian fighter jets operate in close proximity with two very different strategic objectives.

Where Britain can help the people of Syria is by piling on the diplomatic and political pressure to secure a lasting settlement — working with unlikely partners from Iran to Russia — providing humanitarian relief and playing our role in giving overt and covert advice and support to the Free Syrian Army and other moderate forces within Syria. Cameron said this a year ago. It was the right approach then and it remains so now.

Yesterday, Tony Blair rightly said that we should ensure that any final peace agreement in Syria has our imprint on it, and not just Russia’s. But playing catch-up with other people’s bombing raids is hardly the most effective way of doing so.

Dropping bombs on Syria is, in many ways, the easiest option: it gives the impression of doing something about the conflict, when in truth it will do little to alter the rhythm of war.

The Government wants to reassert itself on the international stage. It hates standing idly by as others send their war planes into Syrian skies. The Prime Minister senses a change in the public mood because of the refugee crisis. And the Conservatives sense a political opportunity in the wake of Corbyn’s election as Labour leader. But none of those factors is a good enough reason for acts of war.

Parliament should not be asked to pronounce on a pinprick bombing adventure that will do little to change the tragic circumstances on the ground. We should focus British efforts where they can really make a difference — and Parliament should push the Government to demonstrate it has a strategy to do just that.