Vladimir Ashurkov says he has learnt to be vigilant around fellow Russians

Russians in Britain fear that as many as half their fellow expatriates are informants for the Kremlin, a report says.

Suspicion and paranoia were fuelled by the mass expulsions of Russian diplomats from 26 countries in response to the poisoning of the double agent Sergei Skripal.

Some Russian spies in Britain operate according to “a rather simple playbook” and take little trouble to cover their tracks, according to the research published today by the Henry Jackson Society think tank.

Sir Richard Dearlove, the former MI6 chief, welcomed the report, which “forcefully reminds us that Russian intelligence activity in the West is still large-scale and intrusive”.

He said: “We need to devote significant resources and expertise ourselves to monitoring and blunting this threat to our national