The Split star Stephen Mangan leaves Lorraine gobsmacked over 'throuple' detail

Lorraine Kelly was left covering her face in shock after he shared a revelation about a new work project which took her by surprise.

Stephen Mangan, known for his role as Toby Stephens in The Split, appeared on the ITV daytime programme to chat about the series' return, which will take viewers to Barcelona. He also unexpectedly announced that he and his BBC One co-star Nicola Walker would be teaming up for a West End play - a piece of news that Lorraine and fans were completely unaware of.

During the show, avid fan Lorraine prodded Stephen for details about the upcoming play set for next year. "You and Nicola who are good mates as well are going to be working together next year as well aren't you? she inquired. To which Stephen responded: "Yeah, we're doing a play in the West End and it's a very different kettle of fish."

Lorraine, unable to contain her curiosity, pressed for more information but was left utterly astounded when Stephen disclosed a significant detail, reports the Mirror.

"It's very grown up, it's funny it's very sexy, it's about a throuple," he revealed, leaving the usually talkative TV host at a loss for words.

"What! What," Lorraine exclaimed, both of them bursting into laughter before Stephen elaborated: "So we're married again, we're back together but our marriage is a little bit stale a bit off the boil and she meets another woman and it's like 'is that a good idea or not?"

Lorraine expressed her intrigue, remarking: "See I find that fascinating because when you actually start thinking about it the ramifications for a relationship are huge, their enormous and although it might sound very naughty and everything... and again messy."

Stephen countered: "I think you're going through a door that you can't get back through," to which the new grandmother conceded: "This is very 'true'."

He continued: "You're moving your relationship into an area where it's... but a lot of people that I meet, especially the younger generation tell me it's such a thing and a throuple is now... with even four people in a relationship."

With a playful smile, Lorraine quipped: "Not me I haven't got the time nor energy."

Stephen and Nicola Walker will reunite onscreen for The Split: Barcelona, airing on BBC One on December 29. The duo, who play lawyers Hannah and Nathan, have navigated a tumultuous separation since the series began.

The upcoming instalment takes them to Spain for their daughter's wedding.

Lorraine airs weekdays on ITV1, from 9am.