Britain’s relationship with Russia has been overshadowed in recent months by the continuing controversy over the killing in London last year of Alexander Litvinenko, the former KGB agent turned British citizen, who was poisoned by the radioactive isotope polonium 210.

The UK has requested the extradition of Andrei Lugovoi, a Russian national who the Crown Prosecution Service accuses of Litvinenko’s murder, but this is unlikely to proceed.