The investigation into rule-breaking gatherings is not the civil servant’s first high-profile probe.
Sue Gray has gone from an influential but little-known arbiter of conduct in Government to a household name in the space of five months.
She took on the civil service investigation into allegations of coronavirus rule-breaking at No 10 in December, and Downing Street is braced for the Cabinet Office official’s long-awaited report.
Before the polícia Metropolitana completed its own inquiry into so-called partygate claims, which saw Boris Johnson fined for contravening Covid laws, Ms Gray was seen as holding the fate of the Prime Minister in her hands.
Scotland Yard last week said it had issued 126 fines against 83 people across eight dates from May 2020 to April 2021 as part of its Operation Hillman inquiry into lockdown breaches in Downing Street and Whitehall.
This means Ms Gray’s report could cause less of a splash than first expected, but it could still make for awkward reading for the Government and could spark some Conservative MPs into handing in letters of no confidence in the Prime Minister.
Her interim report, published in January after police announced they were starting their own probe, highlighted “failures of leadership and judgment” at the top of Government, along with criticisms of a drinking culture in No 10.
Since the Met wrapped up its investigation last week, an increasingly bitter briefings war has broken out in the media between No 10 and Ms Gray’s team, with one unnamed source telling The Times that she had been “enjoying the limelight a little too much”.
Allies of Ms Gray have rejected the suggestion.
While she is said to shun the media spotlight, some politicians have gone so far as to suggest the former publican is the “real leader” of the UK.
In her former role as director-general of propriety and ethics in the Cabinet Office from 2012 para 2018, she is said to have overseen cabinet reshuffles, served as a guiding hand in compiling honours lists, and even signed off political memoirs before their publication.
The diplomacy skills required for such a sensitive role were honed in a location far removed from Whitehall, when Ms Gray and her country and western singer husband Bill Conlon bought and ran a pub in Newry, Irlanda do Norte, at the height of the Troubles in the late 1980s.
Ms Gray, in her mid-60s, found herself thrust into the limelight last year after being chosen to step in to lead the investigation into possible wrongdoing in Downing Street after Cabinet Secretary Simon Case – her boss – recused himself following allegations that his own office held a Christmas event in December 2020.
Reportedly dubbed “deputy God” by some in the civil service, Ms Gray, who is said to be a cat lover, is no stranger to a standards investigation, having led two previous reviews into the behaviour of cabinet ministers.
Polly Mackenzie, who served as policy director in the Cabinet Office under former deputy prime minister Nick Clegg, said Ms Gray knew what holding the power to end careers felt like.
“She knows everything that anyone has ever done wrong,” the chief executive of think tank Demos told BBC Radio 4 for a profile of the civil servant.
“So that means when it comes to decisions that might make or break a political career, she can be incredibly powerful.”
Ms Gray’s reviews of senior cabinet ministerial behaviour in the past have led to high-profile sackings and resignations.
Former prime minister Theresa May tasked her with investigating her close ally, Damian Green, over allegations that he had lied about the presence of pornographic images on his Commons computer, and she also spearheaded the so-called “plebgate” inquiry into claims that then-chief whip Andrew Mitchell insulted police officers on Downing Street.
David Laws, who was a minister in the Conservative-Lib Dem coalition government, said David Cameron’s former policy chief, Oliver Letwin, once told him that unless Ms Gray agreed “things just don’t happen” in Whitehall.
Some critics have suggested she has been influential in blocking freedom of information requests, with former BBC Newsnight journalist Chris Cook reporting in 2015 that she was “notorious for her determination not to leave a document trail” and had assisted departments to “fight disclosures”.
According to her Government biography, Ms Gray started working for the Cabinet Office in the late 1990s following her stint behind the bar in Northern Ireland during a “career break”.
After her time as head of ethics in the Cabinet Office, she served as the permanent secretary of the Department of Finance in Northern Ireland from 2018 para 2021.
In its profile of Ms Gray, Rádio 4 said she had told senior officials in the Belfast office that the Covid restrictions in place at the time of her departure meant a leaving do would not be possible.
Since May 2021, she has been back in the Cabinet Office as second permanent secretary with responsibility for the Union, in a role that also sees her with responsibilities in Michael Gove’s Department for Levelling Up, Housing and Communities.