Who is Sergei Skripal? A double agent who was given refuge in UK in spy swap

Described by neighbours as a quiet man who dressed casually and drove a BMW, Sergei Skripal was once colonel in Russian military intelligence before he was convicted of spying for MI6.

The 66-year-old was accused of working for MI6 over several years, in particular disclosing the names of several dozen Russian agents working in Europe.