What happened

How advice has changed

Sunday March 4

1.30pm Sergei Skripal and his daughter, Yulia, leave home and head to the centre of Salisbury. After eating lunch at Zizzi’s on Castle Street they go for a drink at the nearby Mill pub.

4.15pm The pair collapse on a park bench close to the Maltings shopping centre. A member of the public dials 999. Yulia is airlifted to hospital and Sergei is taken by ambulance. Investigators visit the scene and attend Mr Skripal’s home.

Monday A major incident is declared at Salisbury District Hospital with initial reports

suggesting it is drug related. Mr Skripal is identified as a former Russian double agent who came to Britain as part of a spy swap deal. Parts of Salisbury are cordoned off. Wednesday

Counterterrorism police, now leading the investigation, confirm that the substance involved is a nerve agent and say they are treating the incident as attempted murder. Public Health England (PHE) insist there is no immediate risk, despite the fact a police officer, who attended the scene is in intensive care.

Thursday The police officer, Det Sgt Nick Bailey, is revealed to be among 21 people who received treatment.

Friday Counterterrorism police call in military to assist with the removal of objects and vehicles from key locations. Sunday March 11

PHE advise anyone who visited key locations around Salisbury last weekend to wash clothes and wipe possessions with antiseptic wipes.

The military and police seal off a police station and offices and remove vehicles from the car park.