Cameron will not ask for a vote on Syria action unless he is confident he will win

One of the most significant sentences in the statement from Downing Street on Thursday morning - on the case for airstrikes in Syria - is the one on whether to call a vote in the House of Commons.

Because David Cameron has made it clear in recent days that MPs will not be asked to vote on military action against the IS/ISIL group in Syria unless he is confident he will win it.

So if Downing Street announces that it plans to hold a Commons vote, the planners in the Ministry of Defence might as well get to work straight away.

The Prime Minister is not going to risk being defeated as he was in 2013 on a plan to conduct airstrikes against President Assad in Syria.

A second rejection would, said Downing Street sources, "hand ISIL a propaganda victory".

So where are we on numbers in the House of Commons?

In short, no one really knows.

There are fewer Conservative MPs who oppose the plan this time.

In 2013, there were 30.

Now perhaps around 15 to 20.

David Cameron will not risk another defeat over strikes in Syria. Credit: PA

And those on Labour's benches who might be prepared to consider supporting military action will depend on the strength of Mr Cameron's arguments on Thursday.

But currently, they are thought to number 50 to 60.

Clearly, Jeremy Corbyn will not be among them.

He will oppose and he has yet to decide whether to give his 233 MPs a free vote or whether to whip them to vote against airstrikes.

So the Shadow Cabinet (also split on this issue) will meet after the Prime Minister's statement on Thursday and then again on Monday afternoon after consulting their constituents over the weekend.

The free vote decision will be announced before Labour MPs meet at their weekly Monday night gathering in the Commons.

Remember, the UK does have parliamentary approval to target the so-called Islamic State group in Iraq.

But in Syria, RAF jets can only carry out surveillance missions - not airstrikes.

If Downing Street can lock in enough Labour and DUP members to offset the Tory opponents of airstrikes - there could be a vote next Tuesday.

And Britain could be sending missiles towards ISIL targets in Syria as soon as next week.

Jeremy Corbyn will oppose action in Syria, but what about his MPs? Credit: PA