Russia 'has spy in UK's intelligence, cyber and security agency GCHQ', says ex-KGB defector

Defector and former KGB major Boris Karpichkov claims to have new evidence that the maths genius was murdered to protect Russia's mole

A Russian spy who infiltrated Britain's top secret Government Communications Headquarters (GCHQ) base is passing secrets to Moscow, a former major in the KGB says.

Defector Boris Karpichkov claims to have new evidence back…