Sarah Brown called Gordon her hero, Samantha Cameron insisted David was “incredibly funny”, while Akshata Murty said Rishi was her best friend. When Marie-France van Heel spoke about her husband, Andy Burnham, in a rare public interview a decade ago, she joked that she had noticed his “good looks … and monobrow”.

The spousal humanising of a party leader is a well-worn political tool, but van Heel is likely to be a very different prime ministerial partner. The former senior marketing executive is poised to play a more significant role in promoting Britain than any other spouse in the last two decades, stepping up her political engagements after stepping back from her own corporate career.

Van heel has chosen a political adviser to help her navigate the role at home and promote the UK’s interests overseas, the Guardian understands.

She has shifted her role at Be.EV, an electric vehicle-charging network based in Manchester, quitting her job as chief customer officer to give her schedule more flexibility, while remaining on the company’s board.

While it is standard for the partners of prime ministers to have taxpayer-funded office support, van Heel has taken on a former special adviser to a cabinet member and is expected to play a more significant role behind the scenes than the previous prime minister Keir Starmer’s wife, Victoria, who continued her work in occupational health for the NHS throughout her husband’s tenure.

Last week, she travelled with Burnham to the UN general assembly in New York, attending a lunch hosted by the US first lady, Melania Trump, as well as holding meetings with Ukraine’s first lady, Olena Zelenska, and the Canadian prime minister’s wife, Diana Fox Carney. The UK is holding the G20 presidency next year and the G7 presidency the year after, and van Heel is seen as a valuable addition to the UK’s diplomatic vanguard.

At the Labour party conference this week, she posed for photos with the Labour Asians Society and attended a fringe event on apprenticeships. One gushing corporate communicator later wrote that she had spent half an hour making apprentices “feel like the most important people in the room”, adding that she was “a total class act”.

Van heel and her team are now speaking to charities and leaders and weighing up how to make best use of her “impressive” personality and professional experience to champion causes. They will be lucky to have her, said Rose Caldwell, the chief executive of Plan International UK, where van Heel was a trustee until July. “She brought valuable insight and unwavering commitment to the role,” she said. “She really made a lasting contribution to our mission of advancing equality for girls.”

Born in Roslyn, Pennsylvania, to Dutch parents, van Heel grew up in the Netherlands and Belgium and met Burnham on her first day as a student at the University of Cambridge. In a campaign video for his mayoral campaign, she asked the future PM if he remembered his response to her question about what he wanted to do with his life. “You said you wanted to be an MP,” she said. “Yeah. And I left the room at that point.”

After almost a decade in Manchester, van Heel is something of an unknown quantity in Westminster, but insiders say she has already impressed staff behind the scenes. “She’s incredibly cool,” said one source. “She’s very nice, very smart … she just gets it.”

The clearest picture of the prime minister’s partner has come from Burnham himself. Speaking to Elizabeth Day for the How to Fail podcast, he said that his wife of 26 years was “forthright” when she thought he had got something wrong. “She’s Dutch, and they don’t hold back,” he said. “They’re pretty plain speaking, and yeah, I’ve been on the receiving end of a lot of that over the years.”

Burnham has recalled finishing an interview when he was an MP and seeing a text from his wife exhorting him to “ANSWER THE F***ING QUESTION”. When he told van Heel he was planning to run to be Labour leader earlier this year, after failed bids in 2010 and 2015, she did not hold back. “She was like, ‘Oh, not again! They’ve told you twice. They don’t want you. Why again?’” Burnham said. “She took some persuading, to be honest, because I guess she didn’t want to see me go through it all again […] But she gives me good advice.”

But there are earlier hints, too. Much has been written of van Heel’s appearance on the Cilla Black TV show Blind Date in 1992, when she punctured the private school hubris of “Will from Surrey” – otherwise known as Will Harris, who later became the marketing director for the Conservative party.

But a full viewing of the video – in which van Heel flicks Harris’s wandering hand off her knee, before smacking her unfortunate date with a cushion when he calls her a “fridge” – gives a sense of her blunt confidence and quick wit. When Harris says his “interests were honourable”, she retorts: “I didn’t have any interest at all.”

Officially, Downing Street will say only that van Heel, who has three adult children with Burnham, is supporting her husband and “advancing UK interests” as spouses have done before.

Where van Heel’s energy will be directed now that her husband has reached No 10 is still being mapped out, but it is likely that she will be the most active – and potentially influential – prime minister’s wife since Sarah Brown at the start of the century. Brown’s diaries from Downing Street note there is “no formal spouse job to step into […] no permanent office, no salary, no allowance, no pre-set duties or official role, not even an official title” for the prime minister’s wife. It is a job that van Heel did not ask for, and may not even want – but it looks likely she will make it her own.