Keira Knightley struggled over ‘disgusting’ kiss for Christmas advert

But a production source claimed that Knightley found the kiss scene unexpectedly difficult.

They added: “She’s done dozens of screen kisses, but this one threw her. She joked that it was kind of disgusting – more because of the awkwardness than anything Joe did.”

Another insider claimed: “She struggled with the moment. She said it felt bizarre trying to be romantic in a supermarket aisle with a camera two inches from her face.”

Wilkinson, who had only performed two on-screen kisses before this ad, was also nervous.

He said: “I thought, Keira Knightley has probably kissed, I don’t know, 50 people on screen, I guess.” He remembered breaking the tension by blurting out his discomfort.

Wilkinson said: “Then I just said, ‘I think this is weird, kissing is weird,’ and she said, ‘It is, isn’t it? It’s really weird.’ It broke the tension.”

Another source claimed that Knightley’s discomfort was not helped by Wilkinson’s deliberately unvarnished appearance.

“He shows up with this wild beard and hair, and makes dirty jokes between takes — all very Joe — and she’s meant to immediately melt for him,” the insider said.

“She got the giggles more than once, but he’s certainly not a leading man.”

Despite her hesitation, colleagues said Knightley remained professional and spoke warmly about her daughters running home after the film wrapped.

A friend close to the actress said: “She loves to work, but she is a hands-on mother. Every long day is balanced with family time, and that is her real priority.”

Wilkinson, meanwhile, is enjoying a career surge. The Famous traitors contestant, who lives in Brighton with his wife, Petra Exton, and adult stepson, has built a devoted fan base through series such as Miranda, After life, And Sex education.

His new status as an unlikely heartthrob seems to amuse him more than anything.

He said: “I wouldn’t say ‘sex symbol’ – that makes me cringe.”