Britain faces a present threat, Norfolk MP Keith Simpson has warned ahead of a vote tonight about whether to extend air strikes into Syria.

The privy councillor, who joined the Intelligence and Security Committee earlier this year, said the agencies had identified a present threat now 'to us, to our constituents and to our allies in Europe' and they could not guarantee to thwart everything.

He said the MPs should look at the present situation, describing the Iraq War as the 'elephant in the room'.

But he said: 'Our predecessors sat in the Commons in the 1930s determined not to have another Great War. The Labour party were divided, there were pacifists, those who swished to have national security. My own party supported appeasement which the overwhelming majority of the British public did. They genuinely wanted to prevent another war. They failed because they were dealing with people in other countries not prepared to negotiate.

He also described how former prime minister Anthony Eden had believed Nasser [the Egyptian president] was another Mussolini [the fascist leader in Italy in the 1940s], and therefore he was prepared to take action which was the wrong action at the time. 'I feel we should put on one side where we stood on this other campaigns,' he said.

But he returned to the second world war on the issue of the Prime Minister's claim there would be an army of 70,000 'moderates or immoderate who may or may not be ground forces'. 'I have to say to that we know in the second world war that when Churchill and Roosevelt [the UK and US war time prime ministers] were looking at resistance in Europe it was dreadfully difficult to find out if people were communists, non-Communist, gaullists. Their criteria at the end of the day was were they fighting the Nazis,' he said.

'The prime minister has laid out a set of proposals and I would urge the house to vote with him on this occasion,' he added.