Flyers with her picture were placed on seats at the Michelin-starred Cinnamon Club in Westminster — as if guests at the launch of her campaign would need a reminder of who she is.
Only a few minutes later, they were in no doubt.
Amid a heatwave in Britain, Ms Mordaunt displayed her cool demeanour in a well-received speech on Wednesday.
If the trade minister achieves enough MP votes to be one of the final two candidates, her opponents will have reason to be concerned as she is currently most popular among the Conservative grassroots.
The Royal Navy reservist has demonstrated that she can hold a room as well as tear a strip off the opposition. This was shown by her evisceration of the deputy leader of the opposition Labour Party, Angela Rayner, in a House of Commons debate last year.
That could explain why the survey of the ConservativeHome members’ panel, that has proven accurate in the past, found Ms Mordaunt would beat the former chancellor Rishi Sunak by 58 per cent to 31 per cent, and Foreign Secretary Liz Truss by 51 per cent to 33 per cent.
In a survey by YouGov, she achieved 12 per cent, followed by Mr Sunak on 10 per cent and Ms Truss on 8 per cent.
In the first round of the Tory leadership vote on Wednesday night, Ms Mordaunt's credentials were confirmed when she received 67 votes to finish second behind Mr Sunak (88). Ms Truss came third with 50 votes before the next ballot on Thursday.
Until Wednesday, Ms Mordaunt had largely remained silent, apart from releasing a slightly pedestrian video announcing her candidacy.
But, after largely winning over the press with her presentation, Ms Mordaunt is rapidly emerging as the dark horse who could win the race to become Britain’s next prime minister.
Speaking largely without notes, the former defence secretary delivered calm, measured arguments that did not over-promise.
“Whitehall is broken and trust had to be restored,” she said, speaking from a lectern with her catching “PM4PM” logo and with a rather tattered — perhaps battle-scarred — British union flag behind her.
A mark of her growing power was the mass assembly of leading Westminster commentators packed in shoulder-to-shoulder in a small room.
Ms Mordaunt did not overstate her service background, but did refer to witnessing as a 9-year-old the Falklands task force set sail from Portsmouth to retake the South Atlantic islands from Argentina in 1982.
“My country stood up to bullies,” she said to applause. "[Britain] does not need a new role in the world, we just need to be ourselves."
On defence, where she briefly served as secretary of state in 2019, Ms Mordaunt vowed to “take tasks off the armed forces” by introducing a new “civil defence force”.
She also pledged to slash fuel tax and raise the tax-threshold of 40 per cent in line with inflation.
Whether she has the chance to deliver on her policies could prove the most fascinating fight in the coming days. Many commentators believe Ms Mordaunt is likely to reach at least the last three candidates during MPs’ voting.
Her pitch without notes was brave and she had distinct breaks between making points, showing the polish of speech-training that instructs the famous “Obama pause” during oration.
Also, without referring to a written narrative is something that could charm Conservative Party members, as it did for former prime minister David Cameron in 2005. Those 200,000 activists are the path to power as they will vote for one of the last two remaining candidates that the parliamentary party puts forward.
Ms Mordaunt was introduced by fellow Brexiteer Andrea Leadsom, who came second in the 2016 leadership race. She was supported by a broad range of MPs from veteran Brexiteer David Davis, the outspoken Alicia Kearns, and the eccentric Michael Fabricant.
Who will replace Boris Johnson?
Ms Mordaunt has several advantages over her current closest rivals, Mr Sunak and Ms Truss.
She did not serve in Boris Johnson’s Cabinet, distancing herself from the toxicity of scandal and untruths. She is an original Brexiteer, unlike the convert Ms Truss. She does not carry Mr Sunak’s baggage of a police fine for coronavirus lockdown rule-breaking or questions over his wife’s tax status.
She also has strong social liberal views, that might appeal to One Nation Tories, although her apparent “woke” comments on transgender people have not endeared her to the right wing.
Asked about sexist comments currently being made behind-the-scenes about her, Ms Mordaunt stridently responded: “It’s because I’m a threat to their campaign.”
But she was also gracious in thanking Mr Johnson “for delivering Brexit”.
On the Cinnamon Club performance, it became clear why she is rapidly becoming the candidate to fear.
Towards the end of her fluent, 12-minute speech, Ms Mordaunt insisted she would be the “candidate that Labour fear most”. As the cheers faded, there must have consternation among the opposition ranks.