'Novichok is reported to be 5–8 times more lethal than VX nerve agent and effects are rapid, usually within 30 seconds to 2 minutes.' - Ian Greaves FRCP, FCEM, FIMC, RCS(Ed), DTM&H, DMCC, DipMedEd, RAMC, Paul Hunt MBBS, DipIMC(RCSEd), MCEM, MRCSEd, DMCC, RAMC, in Responding to Terrorism, 2010.

Mar 7

Police activity continues inside and outside the home of Sergei Skripal in Salisbury as he and his daughter Yulia remain critically ill in intensive care

After event Skripal crime scene on 4 March 2018

Skripal crime scene, early evening of 4 March 2018.

              Two people encircled in previous image. Image crop by @JohnDelacour

With thanks to @JohnDelacour for technical assistance. 

'Two women have been taken in an ambulance from Sarum House which is a building in between Zizzi and Tesco.' - Spire FM, Incident in Salisbury city centre by Zizzi, 7 March 2018.

One of the women appeared to have a ring on her left hand. The other woman appeared to lighter and wavier hair, with apparently no ring on her left hand:

The two women appeared in a spliced youtube video: https://www.youtube.com/watch?v=qowRoxI0fS0