MP and military historian Keith Simpson has called for Britain to take a tough stance with Russia after a double agent and his daughter were poisoned.

Broadland Tory Mr Simpson recalled the action taken by London in the early 1970s when 100 Russians were expelled. His comments come on the back of the poisoning of former spy Sergei Skripal and his daughter Yulia.

Police have now confirmed the substance used was a nerve agent and it is suspected Russian operatives were involved. The pair remain critically ill.

'It is more complicated than it was 50 years ago,' Mr Simpson, a member of the Intelligence and Security Select Committee, said. 'In the early 1970s the level of Soviet penetration was enormous and we made the decision – which was high-risk – to throw out 100 Soviets who had diplomatic cover. 'This was a complete gobsmacker as far as the Russians were concerned and undoubtedly reduced their activity. There is always a possibility we could do the same thing.

'Historically the agencies prefer not to throw people out, they prefer to monitor them. But what we have seen in the last 10 years is the establishment of Putin's authority the fact there is this very opaque relationship between Putin's security agencies, criminal gangs and the oligarchs and the fact that Putin or his associates will give the nod for things to take place but their finger prints won't be on it.

'And since the establishment of the Soviet state in 1917 its intelligence and security agencies have always been quite clear that people they regard as traitors, they will punish them.

'Expelling people again probably wouldn't make a difference to Russian behaviour and I certainly wouldn't advocate expelling anything like 100 again but we could smaller numbers. They would no doubt retaliate of course.'

And Mr Simpson also hinted that more funding would be needed as the threat from Russia intensified: 'The National Security Council is going to have to tell our agencies that to monitor Russian activity – which they are already doing obviously – they are going to have to put more resources into it.

'And they are going to have to not only monitor the kind of people they might use but also you need to think in terms of what protection you are going to give people who have been our agents.'