She stepped out on stage in a bright coral suit and heels, a pop of colour against the blue backdrop - beaming across at the delegates and describing herself as "a bit of a surprise addition… and a surprise for my husband too, who has no idea what I'm going to say".

Number 10 insist this was the case; that Mr Sunak, a man who prides himself on being across the detail of everything, had been left in the dark about the contents of her speech, which we're told she had written herself.

Mrs Murty is not usually someone who seeks out the limelight, scalded no doubt by the row over her non-dom status and fabulous wealth as the daughter of an Indian billionaire.

Indeed, the controversy surrounding her tax status, when it was uncovered in 2022, was widely believed to have derailed her husband's hopes of ever standing for the leadership.

She does now pay UK tax on her international earnings, but it's an ever-present reminder of her status as one of the true global elite, and regularly weaponised by Labour at PMQs to paint her husband as impossibly detached from the reality of the cost of living crisis for ordinary working people.

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But ahead of possibly the biggest speech of her husband's life - team Sunak decided to take a gamble that the combination of her loving personal tribute and the star power of her glamorous appearance would enhance, rather than detract from the prime minister.

She was impeccably dressed in a £612 jacket and trousers from the British brand The Fold, a favourite of the Princess of Wales.

Mr Sunak is a self-confessed geek, a technocrat whose speeches can sometimes appear robotic or patronising; after days of criticism for his "tetchy" response to questioning about the HS2 decision, he badly needed humanising, and his wife's introduction painted a very different picture.

The speech was personal and glowing with praise for her 'best friend' - "he is fun, he is thoughtful, he is compassionate and has an incredible zest for life".

Watching offstage, the prime minister seemed quite emotional as Mrs Murty took us back to the early days of their meeting at university in America at the age of 24, and the challenges of long-distance relationships.

But the personal swiftly segued into the political here, as she claimed that she wasn't attracted by his appearance, but his "deep love" for the UK and "his sincere desire to ensure that as many people as possible had the chance to have the opportunities that he was lucky enough to have".

After a slightly wobbly start when she seemed unclear about which microphone to use, it was a confident, sweet performance, with jokes about her husband's love of cheesy romcoms, but not Emily in Paris. Delegates in the hall seemed to lap it up, and she was mobbed on her exit almost as enthusiastically as her husband afterwards.

"Murty's speech reinforces Sunak as a family man and shows that they are a unit with stability, something which I think many members and voters will be pleased to see," said political communications consultant Laura Dunn. "It was a bold move."

But it's a highly unusual move for a British political leader. The last, and only time a prime minister has been introduced in their spouse was in 2009, when Gordon Brown's wife Sarah memorably described her embattled husband as "my hero".

But at the 2010 election just months later he suffered a devastating defeat. For some watching, the parallels were clear: turning to Mrs Murty was a sign of weakness, with an implication that the PM needed to borrow some of his wife's sparkle to make up for his own lack of charisma.

Denis Thatcher - Norma Major - Cherie Booth - Samantha Cameron - Philip May - Hugh O'Leary - all were happy to stay in the background.

Even media appearances have had a chequered history: Philip May gave a joint interview with The One Show which was widely criticised for Mrs May's division of "blue jobs" and "pink jobs" and him taking the bins out ("a traditional boy job").

But there are signs Downing Street have been moving towards a more confident public role for the PM's wife for some time.

She made high profile appearances on his recent trip to India for the G20 - understandable perhaps, given her own citizenship, but it was seen as fairly successful. Mr Sunak said "it was lovely to have her with him" and praised her help in building relationships with other leaders and their spouses.

Last month she gave her first television interview to the Sky Kids programme, FYI, in which she described the power struggle between the family dog Nova and Larry the cat, and talked about the "range of opportunities" that she'd been exposed to since moving into Number 10.

Mrs Murty's own parents clearly have a close working relationship and partnership; her mother, Sudha helped her husband Narayana to establish the IT firm Infosys, which made their fortune, and they continue to work together on philanthropic projects.

Sudha Murty hit the headlines earlier this year after commenting that behind every successful man there stands a woman - and boasting that while she had made her husband into a successful businessman (and one of India's richest men) "my daughter has made her husband prime minister of the UK".

In America, political spouses are always much more prominent, and it's typical for candidates to be introduced by husbands or wives celebrating their personal qualities.

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But from Michelle Obama and Jill Biden to Hillary Clinton - the role of presidential first lady is much more political, and high profile, than the partner of the UK prime minister. Clinton of course went on to become secretary of state and to seek the presidency herself.

It doesn't seem that that's what Mrs Murty is after. But Number 10 say the pair have an "extremely strong partnership" and she is clearly determined to do what she can to help in his uphill battle to stay in Downing Street after the next general election.

"Gatecrashing" her husband's speech livened up the culmination of a fractious Tory party conference and provided a new insight into what had previously been a relatively private relationship.

And while amongst political opponents the spotlight on Mrs Murty has reignited the conversation about the couple's vast personal wealth; the gambit here is on getting general voters to look at the PM in a new light.

Going by the number of newspaper headlines her appearance has generated - it's certainly done that.