Poisoning of Sergei and Yulia Skripal
The agent could be applied with an aerosol spray or transported in liquid form.
Boris Johnson says it proves Russia was behind it.
Even their medical future is unclear.
Yulia was discharged from hospital on Tuesday.
Her father Sergei should be able to leave 'in due course'.
Government is trying to deflect criticism over austerity and Brexit, Corbyn ally tells Kremlin-backed broadcaster
Russian Embassy seizes on discrepancy
Russia is accused of poisoning her and her father.
There are fears she may never recover fully.