The way Boris Johnson’s fiancee Carrie Symonds was briefed against in the media was sexist, according to Samantha Cameron.
Ms Symonds, a former Conservative Party head of communications, was derogatorily termed “Princess Nut Nut” by allies of Dominic Cummings, according to briefings in the press.
Mr Cummings left his role as de facto chief of staff to the Prime Minister at the end of last year after a reported power battle with Ms Symonds over the running of Downing Street.
Fashion designer Mrs Cameron, who lived in Downing Street for six years while her husband David Cameron was prime minister, said Ms Symonds had been treated unfairly.
Asked on BBC Radio 4’s Women’s Hour whether the description of Mr Johnson’s wife-to-be had been “flagrantly sexist”, she replied: “I think it is.
“I mean, I think it could happen if you were a husband or wife potentially but I think that it is very unfair to pick her out as having some kind of undue influence.”
Mrs Cameron said the term Princess Nut Nut was “very harsh”, and the environment campaigner should not “have that kind of criticism laid at her door”.
She added: “In my view your husband or partner is the prime minister, they’re quite able to take decisions themselves, they have a huge team of advisers.
“And so the idea that it’s the wife, that you’re somehow influencing them over and above what they think or what advice they’re getting from their team, I think it’s kind of demeaning, really, for the Prime Minister.”
During the half-hour interview, Mrs Cameron also spoke about the difficulties Mr Johnson’s Brexit deal has created for her clothing company Cefinn in growing its trade with the European Union.
In 2016, Mr Cameron resigned from Number 10 after the country voted to exit the EU at the referendum, following a successful Vote Leave campaign spearheaded by now-Prime Minister Mr Johnson.
Mrs Cameron, 49, said “teething problems” with the new trade terms mean it is currently “challenging and difficult” to bring goods into the country from outside the UK and to sell them into Europe.
“It is frustrating,” she said. “The majority of our business is in the UK and we do a bit of business in America, but we did have a bit of EU business.
“And obviously you’d like to grow it because it’s easy, it’s on your doorstep. But unless some of the expense and cost of doing that is looked at, it will be challenging. And we might well have to look elsewhere or focus on other areas.”