Arguably the most famous civil servant in Britain, she presided over the Partygate inquiry into the reports of lockdown parties held in 10 Downing Street.
But now, Sue Gray has today sensationally quit from her £170,000 a year job as Sir Keir Starmers chief of staff.
She has now been shuffled to a new role and will become the Prime Ministers envoy for nations and regions.
Morgan McSweeney, Sir Keirs chief adviser who oversaw Labours general election campaign, will replace Ms Gray as the PMs new chief of staff.
Ms Gray said today in a statement announcing her new role that intense commentary around my position risked becoming a distraction to the governments vital work of change.
It is for that reason I have chosen to stand aside, and I look forward to continuing to support the Prime Minister in my new role, she said.
Sue Gray has today sensationally quit from her £170,000 a year job as Sir Keir Starmer s chief of staff
Ms Gray said today in a statement announcing her new role that intense commentary around my position risked becoming a distraction to the governments vital work of change
Grays appointment in May 2023 as Sir Keirs chief-of-staff was marred in controversy.
It was surrounded in circumstances that sparked two investigations and culminated in an explosive political row.
Gray was accused of failing to inform superiors that she was having meetings with the Labour Party leader and his office between October and March, when news of her imminent appointment as Sir Keirs chief-of-staff finally leaked.
During this period, she chose to carry on with the day job, which, among other things, required her to offer impartial advice to a Parliamentary committee that was investigating Boris Johnsons role in Partygate.
It was a terrible mess, and the ensuing scandal was not only damaging what remained of the Civil Services reputation, but also made Gray look distinctly hypocritical: it emerged that she was refusing to cooperate with a Cabinet Office inquiry into her own ethical conduct.
For a woman who has, for much of her recent career, been in charge of running ethics inquiries from the Cabinet Office, that could be described as a punchy call.
Fast forward to March this year and Ms Gray found herself embroiled in a battle of the sexes in the party, with fissures increasingly opening up between Ms Gray and a group of influential advisers known as The Boys.
Dominating that group were election campaign chiefs Morgan McSweeney and Pat McFadden, as well as Matthew Doyle, a seasoned spin doctor who acquired his stone-walling skillset under Tony Blair in No 10.
Mr Doyle, in particular, was said to be worrying that Ms Gray was plotting to carve him out of a future No 10 operation – a plan dubbed Just Stop Doyle by smirking insiders.
According to party sources, Doyle and the rest of The Boys were not being paranoid – she was out to get them.
Grays appointment in May 2023 as Sir Keirs chief-of-staff was marred in controversy
The tensions were not helped by Ms Gray adopting an overbearing and heavy-handed approach to leak inquiries: Sir Keirs embarrassing U-turn over Labours £28billion green investment plan – a muddle which some MPs place at Ms Grays door – was followed by a rancorous inquest into how news of the volte-face reached the media.
She was also claimed to have clashed with Cabinet Secretary Simon Case following Labours general election win.
Among recent bitter briefings about Ms Grays powerful role in No10 were leaks about her £170,000 salary, which is larger than the PMs.
It came as other special advisers saw their pay held down and added to reports of civil war within Sir Keirs No10 team.
The daughter of working-class Irish emigrants from Belfast, shed grown up in London, joining the Civil Service straight after leaving her Catholic state school, when the sudden death of her father from a heart attack had left the family short of cash and put paid to any notion of Ms Gray going to university.
Shed then devoted the thick end of a decade to building her career in Whitehall, only to decide, aged 27, to chuck in the desk job and move to Ulster with her husband Bill Conlon, a professional joiner and part-time musician.
While there, she ran the Cove Bar in the height of the Troubles leading to suspicions later that she was a British spy.
The single-storey roadside pub was in Northern Ireland, just ten minutes from the border with the Irish Republic in a part of rural County Down that had become so violent it was widely known as bandit country.
To this day, local police stations are still protected by razor wire and mesh fences, a legacy of the 1985 IRA mortar attack that killed nine RUC officers and injured 40 others.
She pulled pints while her husband, the lead singer of a country and western band called Emerald, was in charge of entertainment.
It closed down roughly a decade ago and is now a childrens nursery called Kidz Universe. Its pebble-dashed walls are painted a garish shade of yellow and windows have been jollified with images of Disney characters.
Gray has occasionally recalled with affection her time in charge of the Cove Bar during the mid-1980s. When she came to Ulster in 2018, to take up a senior role in the devolved Stormont administration, she told an interviewer: I loved it at the time, [but] Id never do it again.
Morgan McSweeney, Sir Keirs chief adviser and Labours former general election campaign director, will replace Ms Gray as the PMs new chief of staff
Following weeks of speculation about a bitter Downing Street power struggle, Ms Gray will now become the PMs envoy for nations and regions
Asked how she had found being a landlady, she said: Its a very sociable occupation, very hard work. But I loved meeting people.
I think it was in a relatively country area, so a mix of farmers, business people, a great mix of characters, and I got to know them really well and I threw myself into that.
Thats one way of putting it. But in the febrile era when she was serving pints at the Cove, some altogether darker currents were bubbling under the surface.
Back then, the awkward questions about Gray werent being aired in Westminster. Instead, they were circulating in her smoke-filled bar.
Specifically, the grizzled locals found themselves pondering two matters which, in certain circumstances, could involve life and death.
First, was the fresh-faced Londoner whod come to bandit country actually some sort of undercover British spy? And if so, what should they do about it?
Grays CV certainly gave cause for suspicion. The daughter of working-class Irish emigrants from Belfast, shed grown up in London, joining the Civil Service straight after leaving her Catholic state school, when the sudden death of her father from a heart attack had left the family short of cash and put paid to any notion of Sue going to university.
Shed then devoted the thick end of a decade to building her career in Whitehall, only to decide, aged 27, to chuck in the desk job and move to Ulster with Conlon, a professional joiner and part-time musician.
Outwardly it was a strange move, since the couple had no direct experience of the pub trade beyond the fact that Grays mother Anastasia, known as Cissy, had worked as a barmaid in Tottenham.
Among recent bitter briefings about Ms Grays powerful role in No10 were leaks about her £170,000 salary, which is larger than the PMs
Why, then, did they decide — after marrying in March 1985 at Newtownards register office near Belfast — to pour their savings into a pub?
The Cove was no ordinary boozer. Indeed, it was an establishment in a tough corner of Northern Ireland which was famously hostile to British incomers.
Neither Gray nor Conlon, who grew up in the fishing village of Portaferry, an hour and one ferry ride away, had any obvious local connections to the area. What, then, had brought them here? And why did Gray then end up running the gossip-filled pub for a such curiously short period of time — perhaps little more than a year — before suddenly disappearing back to London, where she had a couple of children before resuming her journey towards the higher echelons of the Civil Service?
Was it merely a blip in her career path? Or the behaviour of someone in intelligence?
As it happens, Gray quite recently addressed the spy rumours.
In 2021, she marked her departure from Stormont with an interview in which the BBCs Ulster correspondent Gareth Gordon remarked: Someone put it to me that you were once a spy.
She told Gordon: I know youve had that put to you, um, and, er, I think if I was a spy Id be a pretty poor spy!
If people are talking about me being a spy, um, I think people here have put a lot of trust in me and theyve put a lot of faith in me, and, um, er, you know weve worked really well together and I didnt think Id be working externally in the way I am.
Her tone was light-hearted. But eagle-eyed readers will note that this response falls some way short of an outright denial. Read into that what you will.
Importantly, however, the same interview did see Gray offer an explanation for the relatively short-lived nature of her time at the Cove.
She said that, like many a couple who dream of taking over a pub, she and her husband had quickly discovered that the reality of the job didnt quite live up to expectations. Particularly for Conlon, who soon upped sticks and left.
He [Bill] hated the pub and actually most of the customers didnt like him either because he was quite miserable there.
So after six to eight weeks it was making him a bit fed up, so I sent him back to London and I carried on running the bar on my own, she said.
This is a version of events that happens to dovetail with that offered by a long-standing family friend with whom the Mail spoke with last year. The friend said Bill, who was divorced when he met Sue, thought that running the venue could provide a springboard into a full-time music career.
Music man: Grays husband, country and western singer Bill Conlon
Time, please: The Cove Bar in County Down, which Sue Gray ran in the 1980s, is now a children’s nursery
However, it soon became apparent that Londons pub circuit was, in fact, a far more lively environment for an up-and-coming musician seeking to make a name for himself. And running a quite large pub was hard work.
In all honesty, the whole episode was something of a disaster, the friend said.
People think running a pub is easy, but its a very tough job, and it soon became apparent that the music thing wasnt going to work out for Bill. So essentially they realised very quickly that getting into the trade was a mistake.
Bill went back to London and Sue followed pretty much as soon as they could find someone to take the place off their hands. It was a matter of months in total.
The family friend continued: The idea that they were spying is, in my view, for the birds.
The truth is that they were just young and in love, and probably a little naive, and this was a big adventure that didnt pan out and ended relatively quickly.