To make her point, a drunk Ms Sutcliffe, 47, dramatically pulled down the front of her dress and bared her own left breast to Supt Jackson, 45, one of the conference organisers.
"Look at these. Look at these," Ms Sutcliffe told her. "These are the breasts of someone who has had three children. They are ugly, but I don't feel the need to pump myself full of silicone to get self-esteem." Delivering a final bitter coup de mort, she added: "Sarah, it does not matter how hard you work now because you will always just be known as the girl who had the t** job."
Fast forward six months and the whole tawdry incident has received nationwide coverage in an eye-wateringly detailed disciplinary hearing which has resulted in Ms Sutcliffe - seen here in exclusive photographs taken at another party - being found guilty of gross misconduct, and the reputation of Greater Manchester's women police officers greatly reduced.
At the end of a two-day hearing, the panel which ruled on Ms Sutcliffe's case has recommended that she keep her job despite being brought "to the very precipice of dismissal'.
The three-strong panel, headed by Sir Tom Winsor, even questioned why the officer, who was responsible for counter terrorism and serious crime, drank so much given that she was meant to be on duty from 8 am the following day.
But after hearing from senior colleagues who hailed Ms Sutcliffe as an "inspirational and visionary leader", and influential supporters such as former Labour Cabinet minister turned BBC executive James Purnell, the panel suggested that instead of being sacked she should be given a final written warning, letting her stay in her £109,000-a-year job and keep her £500,000 pension pot.
A final decision on Ms Sutcliffe's fate has yet to be taken, but not surprisingly given her extraordinary behaviour in the early hours of May 6 this year, serious questions are being asked about how she can still be regarded as role model to other women - not least because the hearing heard from her barrister that she has used alcohol as a 'coping mechanism' in the past.
A nd, given what we now know about her use of alcohol, should questions have been asked much earlier about her behaviour? Take these publicly available photos, in which she looks as if she might be the worse for wear, taken in 2009 before her promotion to Divisional Commander in 2010.
Later, in 2010 she was given 'suitable advice' after trying to gatecrash a high-security Labour conference while off duty by pulling rank on a constable guarding a gate. He stood his ground, radioing senior colleagues, who backed his refusal to let her in without a pass.
Then, in 2014, a probe was launched into allegations that she had failed to reveal she was in a relationship with the head of the GMP's professional standards branch, Det Chief Supt Paul Rumney, while sitting with him on a disciplinary panel.
While the Independent Police Complaints Commission (IPCC) found there was no deliberate intention by her to withhold information, it was decided that she should not be allowed to chair any future disciplinary hearings.
And now, in light of this week's hearing, questions are being asked as to whether she should really be allowed to remain as one of her force's most senior officers after an outburst which would in all likelihood have seen a junior officer booted out of the force?
A re-examination of the events of that night certainly raises significant concerns about her conduct, not to mention her attitude towards fellow female police officers.
In fact, according to evidence uncovered during an independent investigation by Durham Constabulary and presented to this week's disciplinary panel, Ms Sutcliffe never entirely supported the conference in the first place.
Supt Jackson told investigators that when she first briefed ACC Sutcliffe about the SWIP event, she replied that she 'struggled to grasp the concept' as she herself had risen through the ranks without such support.
Nevertheless, Ms Sutcliffe happily rubbed shoulders with the likes of ex-MI5 chief Baroness (Eliza) Manningham-Buller, RAF Tornado pilot Mandy Hickson and the Government's integration tsar Dame Louise Casey at the lively event, where entertainment was provided by the likes of Rick Parfitt Jr - son of the legendary Status Quo singer - and DJ Clint Boon, a former member of the Manchester group Inspiral Carpets.
So, too, did Superintendent Sarah Jackson, a married mother-of-two with a MSc in Forensic Science and Technology from King's College London, who joined GMP in 1995, just two years after vicar's daughter Ms Sutcliffe.
At the time of the incident, both women were regarded as leading lights in GMP, shining examples to female colleagues that it is possible to juggle a police career with motherhood.
ACC Sutcliffe, who appeared on BBC's Panorama speaking about gun crime in Salford earlier this year, has been the 'talking face' of the force in several recent high-profile investigations including the doorstep shooting of seven-year-old Christian Hickey along with his mother in October last year.
Supt Jackson, whose grandfather, mother and father were in the police and whose brother and husband are serving officers, is highly experienced and was awarded a Long Service and Good Conduct medal in 2015, after working her way up the ranks as a detective.
Until the events of that night, her relationship with Ms Sutcliffe was said to be 'positive'. In 2014, Ms Sutcliffe herself had interviewed and appointed Jackson to her rank as Superintendent and was for a time her direct line manager. But their apparently friendly relationship swiftly turned sour in the early hours of May 6 in the Mezzanine Bar area of the hotel.
Supt Jackson, who'd had a gin and tonic, a glass of prosecco and half a bottle of wine, was not drunk, while Ms Sutcliffe, by her own admission "drank enough to be very drunk".
According to evidence at the hearing, Greater Manchester Police Chief Constable Ian Hopkins was so concerned that ACC Sutcliffe - who was slurring her words - was drunk, that he asked Supt Jackson to keep an eye on her and make sure she got back to her hotel safety.
"Don't leave me on my own with Rebekah," he said to her, claiming that she was "driving me mad".
After he had left, events took a turn for the worse, with Ms Sutcliffe telling Supt Jackson how another delegate had asked: "Who's that woman over there with the big t**s?" and adding that she "looked ridiculous and was dressed provocatively".
Adding insult to injury she added that since she'd had the 'boob job', she no longer respected Supt Jackson and that she was now judged "on the size of her t**s". Warming to her theme, she said Supt Jackson was 'a laughing stock on the 4th floor' - a reference to the Chief Officer team at GMP and that they had all openly discussed the 'boob job'.
As a result, concluded Ms Sutcliffe, Supt Jackson was regarded as "silly, vain and frivolous" and "promotion was now unlikely because her credibility among chief officers was zero and nobody took her seriously."
Not surprisingly, given the vitriol of the attack at a conference to support women in the police, Supt Jackson, burst into tears. But Ms Sutcliffe carried on regardless, pulling down her dress and revealing her own breast to make her point about self-esteem.
"She was just shouting at me with her breast out," Supt Jackson later told investigating officers.
Ms Sutcliffe ended by telling her colleague she would no longer support her for promotion and that she wanted nothing more to do with her. At that point, the women parted company, with a "mortified, embarrassed and ashamed" Supt Jackson retiring to her room in the Hilton and ACC Sutcliffe going to her room at a Premier Inn. In the morning, a contrite Ms Sutcliffe swiftly apologised for her conduct, admitting she had been "rude and over personal" and saying she thought Supt Jackson was a "fab and brilliant professional".
In a written apology later that month, she added: "I deeply regret what happened and in particular the upset I caused to someone I hold in very high regard. I am determined to learn from my mistakes."
In mitigation, she claimed she had been under a significant amount of stress at the time of the incident -which came just three weeks before her third marriage to a fellow officer - and was 'frazzled' due to both professional and personal issues.
Described by her lawyer as "a role model who is not perfect, who has human frailties", she has undergone therapy sessions after admitting using alcohol as "a coping mechanism". Unfortunately, as we have noted, it is not the first time Ms Sutcliffe has found herself on rocky ground with her superiors.
This latest incident, however, overshadows any past misdemeanours. Aside from the hurt caused to Supt Jackson, the incident has been a PR disaster for GMP and the SWIP conference.
In its aftermath, claims on social media that the conference had been a "brilliant" success were soon overtaken by online gossip about what has become known in the policing world as "#t**gate".
While both officers were derided online for "arguing like fishwives" about their breasts in public, one Twitter user commented: "What not to do? Publicly flashing ones t**s at a showcasing women event."
Then, adding further misery to Supt Jackson's ordeal, others endlessly quipped that the while the conference had been "uplifting", the force's professional standards department was now "abreast of the situation".
In a statement released at the end of the hearing, Supt Jackson, who denies ever having a "boob job", described her ordeal as "distressing".
"Despite not initiating or encouraging the incident, I greatly regret that members of the public had to witness it and that the reputation of Greater Manchester Police has been damaged by it as these are two things I care very deeply about it," she said.
The final decision on Ms Sutcliffe's fate will now be taken by GMP's deputy chief constable Ian Pilling, although she has already received the backing of several influential supporters. Former Cabinet minister James Purnell claimed "the region's police force would be poorer without her and a force for good would be lost".
Meanwhile, counter-terror chief Detective Chief Superintendent Simon Barraclough said that she was "a champion of equal opportunities' and 'one of the best officers GMP has had for a very long time".
Her former boss, Sir Peter Fahy, said she had the potential to become a chief constable, adding that female officers at Greater Manchester Police were subject to "greater scrutiny" than male colleagues with their private lives 'often subject to gossip'.
Ms Sutcliffe's lawyer John Beggs QC assured the hearing this week: "This will not happen again. Despite the humiliation she can rebuild her career, not just for the benefit of her, but for the people of Greater Manchester. She will do so chastened. She won't repeat the mistake. You can be certain of that."
Despite the drink-fuelled shenanigans of this year's event, plans for next year's Senior Women In Policing event are under way.
SWIP17 will be hosted by Sussex Police in Brighton next autumn with the aim of "sharing good practice" and providing "the opportunity for participants to stand together to engender change and continuous improvement".
Some might argue there is still much work to be done.
- Additional reporting: James Tozer
