Met Police Commissioner Cressida Dick has announced Scotland Yard is now investigating several events in Whitehall and Downing Street for potential breaches of Covid laws.
She said while it is not standard procedure for the Met to investigate retrospective breaches, some occasions called for it - insisting the force would "police without fear or favour".
Downing Street has indicated Boris Johnson is willing to be interviewed by police and could hand over diaries, phone records and other evidence.