DAVID Cameron is increasingly confident that a proposal to extend RAF bombing missions in Iraq to Syria will get through the House of Commons thanks to the votes of dozens of Labour MPs, according to a senior colleague.

A Cabinet source claimed there was rising optimism that the Opposition would split, enabling the Prime Minister to win the vote.

“We’re expecting at least 50 Labour MPs to vote with us, so we are confident we will get it through but we’re having to make sure given what happened before,” explained the source, raising the prospect that a vote might even come before Christmas.

The 2013 defeat on a vote to bomb Syria following a lethal chemical attack near Damascus blamed on the regime of President Bashir Assad has made Mr Cameron very wary and No 10 repeated that he would only pursue another vote if there was a “clear consensus in the House”.

While Jeremy Corbyn has repeatedly made clear he is opposed to any bombing in Syria, it is believed that several of his colleagues, including some on the frontbench, would now support a UK Government proposal to extend the bombing.

Such a move could embarrass the new Labour leader but his colleague, John McDonnell, the Shadow Chancellor, has already suggested there might be a case for giving Labour MPs a free vote on the matter. However, such a move would be widely regarded as weakening Mr Corbyn’s control over his party.

Meantime, Downing Street defended Britain's response to the Syrian refugee crisis after it was condemned as "deeply inadequate" by more than 300 lawyers, including a former president of the Supreme Court.

Lord Phillips of Worth Matravers, the first head of Britain's highest court, three other former law lords and Sir Nicolas Bratza, the former president of the European Court of Human Rights, were among the signatories to a statement denouncing an offer to house 20,000 refugees over five years as "too low, too slow and too narrow".

Five retired Lords Justices of Appeal together with Lord MacDonald, the former Director of Public Prosecutions, Lord Carlile QC, the Liberal Democrat peer, and more than 100 other Queen's Counsel, were also on the list.

However, the PM’s spokeswoman insisted the UK could be "proud" of its response to the crisis, which included £1.1 billion in assistance to support refugees in the region, making it the second largest bilateral donor.

No 10 talked down a cross-party proposal aimed at protecting Syrian civilians at the heart of the country’s conflict.