Sue Gray has been sent photographs of Downing Street parties which show Boris Johnson and others next to wine, according to reports.
Reports of the Downing Street party photographs first emerged on Sky News.
It comes as Downing Street has said discussions are taking place between Ms Gray’s “partygate” inquiry team and the Met over what could be published from her investigation report.
The news emerged on a day of confusion over when her report into lockdown parties in Downing Street will be released, following the Met’s announcement that detectives will probe the widely reported gatherings while Covid restrictions were in place.
Speaking to MPs on Tuesday, Boris Johnson said he “welcomes” the police investigation.
Downing Street has signalled Mr Johnson is ready to hand over his mobile phone, documents and to be interviewed if asked to by Scotland Yard.