Of course, who should walk through the door soon after but the man himself, conveniently stopping off for a pint when his journey was halted by a bike puncture.

The unexpected arrival saw Peggy go against her promise and become enthralled. “It’s such an honour to have you here, Mr Mayor,” she swooned. “Oh please, call me Boris,” replied Mr Johnson, his pint briefly in view.

When Peggy later mentioned her political interest, Mr Johnson replied: “If you have any ideas for how I could help Walford, here’s my card.”

“I wouldn’t dream of telling the mayor of London what to do,” laughed Peggy.

Scripted chemistry aside, Dame Barbara clearly made a real-life impact on Mr Johnson, who paid tribute after the star died last year aged 83, following a battle with Alzheimer’s disease.

After topping charts and selling out stadiums and festivals across the world, pop megastar Ed Sheeran spread his musical wings to the fictional world of Westeros in 2017, appearing as a singing soldier in the opening episode of series seven of Game of Thrones.

The brief cameo saw him perform a previously unreleased song around the campfire with a group of Lannister soldiers, and catch the attention of the formidable Arya Stark (Maisie Williams).

Sheeran’s character was referenced again in 2019’s final series after seemingly surviving a run-in with a dragon.

The Shape of You singer is far from the only musician to have appeared on the show. Other cameos included members of Coldplay, Mastodon, Of Monsters and Men, Snow Patrol, Foals and Sigur Ros.

But Sheeran’s fleeting part proved divisive among viewers and cast members. Actor Kristian Nairn, who played Stark family servant Hodor in the show, questioned Sheeran’s inclusion and described the celebrity guest spots in general as “stupid”.

“I don’t like them… I don’t mind going on the record on that,” he told Huffington Post. “I just think it takes you right out of the world.”

“I was like: ‘Why is Ed Sheeran here?’ I mean, Ed Sheeran’s great. He’s a great guy, great musician, but why is he in Game Of Thrones?’

“It’s a fantasy show. We’re all caught in this amazing world and spend so much time and money and talent to create, and all of a sudden there’s a pop star? What?”

The Prince of Wales swapped the halls of Buckingham Palace for the cobbles of Coronation Street when he made a guest appearance for the show’s 40th anniversary in 2000.

The heir to the throne featured in a pre-recorded clip of a news bulletin for the special live episode, shown meeting fictional councillor Audrey Roberts.

The prince also paid a visit to the set and didn’t miss the chance to try pulling a pint at the Rovers Return.

As much a television personality as a politician, Donald Trump had made a string of TV and film appearances – most notably as the host of The Apprentice in the US – before his successful White House bid in 2016.

They included appearing as himself in an episode of long-running NBC daytime drama Days of Our Lives in 2005. The cameo saw Mr Trump share the screen with actress Arianne Zucker and reject the advances of her character Nicole Walker, who pleaded for work by saying: “I think you’ll find I’m a very willing employee, working under you.”

The scene would go on to gain particular notoriety. It was while visiting the set for the episode that he was unknowingly caught on tape making obscene comments about women, and Zucker in particular, to Access Hollywood’s Billy Bush, mere seconds before meeting her.

The unaired footage eventually leaked during his 2016 presidential run and threatened to derail his campaign, forcing a rare apology for what he described as his “locker room talk”.

Zucker later addressed the incident in a lengthy post on Twitter. “How we treat one another, whether behind closed doors, locker rooms or face to face, should be done with kindness, dignity and respect,” she wrote. “Unfortunately, there are too many people in power who abuse their position and disregard these simple principles and are rewarded for it.”

The normally low-key half of the Pet Shop Boys, Chris Lowe played himself in a 1995 episode of the Australian soap. His cameo saw him drive a flash sports car and ask for directions to a recording studio.

Kind-hearted characters Marlene Kratz (Moya O’Sullivan) and Helen Daniels (Anne Haddy) happily helped out but, as older women more interested in Elvis, they hadn’t heard of the group he mentioned being part of.

Mildly bemused as he drove off, the pair were soon joined by the show’s then-heartthrob Annalise Hartman (Kimberley Davies), who, they were surprised to learn, was a huge fan. Distraught at having missed out on the chance to meet one of her idols (in Ramsay Street no less!), she stormed off, thinking about what could have been.

Baby Spice landed a cameo role in a 2003 episode of BBC comedy Absolutely Fabulous, poking fun at her efforts to make it as a solo star after the girl group’s split.

Bunton’s new PR Edina (Jennifer Saunders) and Patsy (Joanna Lumley) were typically haphazard, useless and yet somehow insightful as they tried to remake her career in their own warped image.

The trio had remained friends after working together on the Spice Girls’ Comic Relief single in 1997 and reunited for the Absolutely Fabulous film in 2016.

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