The senior civil servant investigated 16 gatherings, 12 of which are subject to a Met Police investigation.
The report found that ‘some of the behaviours surrounding these gatherings is difficult to justify’, and found ‘failures of leadership and judgement’ in Downing Street.
It also condemned the ‘excessive consumption of alcohol’, stating it is ‘not appropriate in a professional workplace at any time’.
Dan, who is also Mayor of South Yorkshire, said: “Sue Gray’s report reveals a failure of leadership and judgement at the highest level of government.
“It is a damning indictment of the Prime Minister.
“Twelve parties are now being investigated by the Met, including one held in Johnson’s own flat.
“He has continually proven himself to be fundamentally unfit for the office he holds.”