Witness from Porton Down laboratory says ‘many lethal doses’ of nerve agent were applied to Sergei Skripal’s door

A “minuscule” amount of the nerve agent used in the attempted assassination of Sergei Skripal – as small as a sixth of a grain of salt – could have been enough to prove fatal, a government scientist has told an inquiry.

The scientist, an expert in chemical and biological weapons, said “many lethal doses” of novichok were daubed on the handle of the former Russian spy’s front door in Salisbury and it was so pure that it must have been manufactured by a sophisticated laboratory.