If Sergei Skripal was in hiding, he was hiding in plain sight.

The former Russian spy and his daughter are in a critical but stable condition at a Salisbury hospital after being attacked with a rare nerve gas.

Police refuse to speculate about what happened.

SUPPLIED Sergei Skripal seen on CCTV in a local convenience store.

The house in Salisbury Skripal moved into a year after being exchanged in a spy swap was bought for cash and registered in the double agent's own name. He even appears on the electoral register.

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He made little attempt to follow a key tenet of espionage - to be unpredictable and avoid routine.

Instead, the 66-year-old former colonel was a creature of habit: every Sunday he went to the city's Railway Social Club to have a traditional roast, a few pints and a shot of neat vodka. His local shopkeeper recalled his weekly routine of buying 30 of scratch cards.

It is not known whether Skripal was offered a new identity.

But new clues have emerged from Russia, about a man who enjoyed the highs of military success followed by a spectacular fall from grace.

Born in June 1953 in the Soviet province of Kaliningrad, sandwiched between Poland and Lithuania, Skripal became fascinated by the West, tuning into the BBC World Service.

He married Liudmila in 1972, having their son, Alexander, two years later and Yulia in 1984.

His reputation as a fearsome soldier was forged in the Soviet airborne troop known as Desantniki, and in 1979 he joined the USSR's invasion of Afghanistan.

After graduating from the Diplomatic Military Academy he was recruited to the main intelligence unit, known as GRU, where he specialised in spying in Europe, often by serving abroad as a diplomat.

It was while based in Spain in the Nineties that the Spanish intelligence services realised he was ripe for recruitment as a double agent. However, MI6 handled him, in part because his English was so good. In 1995 he was given the code name "Forthwith". MI6 bought a timeshare apartment near Malaga to meet him. He was paid up to ??4,000 each trip and revealed secrets about Russian intelligence officers in Europe.

Around the turn of the Millennium he quit the GRU, but continued to meet colleagues.

In 2004, Skripal was filmed being arrested and convicted of "high treason in the form of espionage". His 13-year sentence to hard labour in Mordovia was cut short in 2010 when he was released in the spy swap.

The following year, he moved to the Salisbury cul-de-sac, inviting neighbours to a house-warming.

It is understood he continued meeting his MI6 handler in a local restaurant. They may have become close friends or he may have remained an intelligence asset.