Renewed outcry over alleged Downing Street parties that breached Covid restrictions has pushed the government inquiry back into the spotlight.
Amid previous allegations of multiple parties, the most recent revelation is an email shared exclusively with ITV News, which provides the first evidence of a garden party on May 20, 2020, when the rest of the country was banned from meeting more than one person outdoors.
The email, sent by the Prime Minister's Principal Private Secretary Martin Reynolds, invites more than 100 employees to "make the most of the lovely weather and have some socially distanced drinks in the No10 garden".
Prime Minister Boris Johnson has refused to confirm or deny the allegation that he was at the May 20 gathering on the basis it could impede on an ongoing inquiry led by top civil servant Sue Gray.
Who is Sue Gray?
Ms Gray is second permanent secretary at the Department for Levelling Up, Housing and Communities.
She took over the investigation into the alleged Downing Street parties after Cabinet Secretary Simon Case quit his role leading the inquiry.
Mr Case had been hit by accusations that his department's office held its own gathering for a partially virtual quiz on December 17 last year.
She was previously director-general of propriety and ethics in the Cabinet Office from 2012 to 2018.
She oversaw the Plebgate inquiry in 2012 after former chief whip Andrew Mitchell was accused of calling a policeman a “pleb” at the Downing Street gates.
She is also part of the panel deciding on who will be next chair of the media regulator Ofcom.
What have others said about her?
Ms Gray has been described as "not a pushover" and "formidable" by Tory MP Richard Holden.
She was also once described by BBC Newsnight’s then policy editor as “the most powerful person you’ve never heard of”.
Labour MP Paul Flynn said the civil servant was “deputy God” in a meeting of Parliament’s Public Administration Committee in 2012 when she oversaw the Plebgate inquiry.
Former Tory MP and Cabinet office minister Oliver Letwin is reported to have said of Ms Gray: “It took me precisely two years before I realised who it is that runs Britain.
"Our great United Kingdom is actually entirely run by a lady called Sue Gray, the head of ethics or something in the Cabinet Office. Unless she agrees, things just don’t happen.”
How did people respond to her appointment?
At the time of her appointment, Labour’s deputy leader Angela Rayner said Ms Gray has the task of restoring public trust.
She said: “At the moment, people are saying ‘which department didn’t have a party?’”
She added: “It’s incredibly disappointing because we all know what was happening when these parties were going on, people couldn’t see their loved ones who were dying, and were making incredible sacrifices.
“So I do think that the investigation has to get to the bottom, but I think that the evidence already is showing that Boris Johnson has set a tone for this government and has allowed this to happen under his watch.”
She said Ms Gray should hand over any evidence of law-breaking which she uncovers to the police.
However, the Scottish National Party’s Westminster leader, Ian Blackford, said “having somebody else from the civil service marking their own isn’t good enough”.
Mr Blackford told the BBC’s Newsnight programme that “it needs to be someone from authority from outwith government, from outwith the civil service. I would suggest that the best way to do that would be by having a judge-led inquiry”.
Why did Simon Case quit his role leading the inquiry last year?
Mr Case's department was accused of two gatherings that broke lockdown rules in December last year - London was under Tier 3 restrictions, where indoor gatherings of two or more people were not allowed.
A source confirmed to ITV News that a partially virtual quiz took place in the Cabinet Office's office on December 17, with six people who were in the office that day, taking part in person in a socially distanced manner. Most attendees dialled in remotely from home.
However, the source said Mr Case did not actively take part but acknowledged staff. The source added he knew the gathering was happening as he had to walk past the group in order to get to his private office.
The Cabinet Office later confirmed these reports in a statement on Friday evening, with a spokesperson telling ITV News: “Staff in the Cabinet Secretary’s private office took part in a virtual quiz on December 17 2020.
“A small number of them, who had been working in the office throughout the pandemic and on duty that day, took part from their desks, while the rest of the team were virtual.
“The Cabinet Secretary played no part in the event, but walked through the team’s office on the way to his own office. No outside guests or other staff were invited or present.
“This lasted for an hour and drinks and snacks were bought by those attending. He also spoke briefly to staff in the office before leaving.”
After Mr Case was tasked with the investigation earlier this month, the Prime Minister’s press secretary insisted that “due diligence has been followed” when asked if the Cabinet Secretary had attended an alleged Downing Street party.
Cabinet Office minister Michael Ellis told the Commons Mr Case “was not at any relevant gathering”.
What is Sue Gray's background?
Ms Gray has been a civil servant since the 1970s, but took a career break in the mid-1980s to run a pub with her husband in Newry, Northern Ireland, where she originally hails from.
She returned to Northern Ireland in 2018 to head up the region's Department of Finance.
She had applied to become Head of the Northern Ireland Civil Service but missed out on the role, with nobody appointed.
Members of the Northern Ireland Assembly said her return to London was a "big loss".