Double agent Sergei Skripal was convicted in Russia in 2006 for spying for Britain.
He and his 33 year old daughter Yukia were found slumped unconscious on a bench outside a shopping centre in Salisbury on Sunday afternoon and both are still in a critical condition.
Police are treating the incident as attempted murder but as yet they don't know how they were contaminated.
Skripal and his daughter dined at the Zizzi pizza restaurant and had a drink at the Bishop's Mill pub in Salisbury.
Skripal helped British intelligence identify dozens of Russian agents in Britain before his arrest in 2004.
He was sentenced to 13 years in 2006 after a secret trial and was swapped for Russian spies caught in the west and given refuge in Britain in 2010
This week British Foreign Secretary Boris Johnson threatened Moscow with sanctions and described Russia as a "Malign and disruptive" state.
Russia denied any involvement and condemned Johnson for "wild" comments and said anti-Russian hysteria was being whipped up intentionally to damage relations with London.
"Londongrad" is the name given to London because of the vast amounts of Russian money which poured into the city since the fall of the Soviet Union.
We all remember what happened to ex KGB Alexander Kitvinenko, murdered with radioactive polonium-210 in London and the British inquiry that found Mr Putin was probably responsible.
A second eyewitness at the scene said the woman was frothing at the mouth and the man's arms stopped moving when he began to throw up.