Actor Derek Thompson bowed out of his role as Charlie Fairhead in Casualty last month, after playing the character for 38 years.

Following his heartbreaking exit from Casualty earlier this year, BBC fans have gone wild after spotting Derek Thompson in another drama series on the channel. The actor, 75, shocked viewers when he made an appearance on Belfast-based series Blue Lights on Monday evening for the second episode of the second series.

Charlie appeared towards the end of the episode as viewers flocked to X, formerly known as Twitter, to express their views on the legendary star’s surprise cameo on the show. One excited BBC viewer penned: “When you see Charlie from Casualty in #BlueLights,” alongside a meme of Leonardo DiCaprio pointing profusely from a Once Upon a Time in Hollywood scene.

Another social media user said: “It’s Charlie from Casualty NOT being Charlie from Casualty #bluelights.” Somebody else expressed: “I have watched Derek Thompson as Charlie for so long that it will be strange seeing him in a different role #BlueLights.”

Yet another asked: “Is that Charlie from Casualty?? #bluelights.” A fifth wrote: “Episode 2 of #bluelights didn’t disappoint. Marching, Dan Gordon, Charlie from Casualty and this classic.”

While a sixth added: “Derek Thompson aka Charlie from #Casualty is playing an absolute blinder in #BlueLights. No mean feat to be one of the most recognisable characters on TV and to switch to a brand new role and make it believable.”

Derek Thompson made a surprise appearance on Belfast-based Blue Lights (Image: BBC)

Derek bowed out of Casualty in March after 38 years in the role of Charlie Fairhead after first joining the medical drama in 1986.

The actor, who got a tribute from a Loose Women star, was the longest-running cast member, having been a part of the series since it’s very first episode.

Charlie was stabbed by a patient as viewers were left on the edge of their seats to see whether he would survive or not.

However, fans breathed a sigh of relief as he managed to survive, with his colleagues applauding him out of the hospital after his treatment

Charlie Fairhead exited the show after being stabbed by a patient (Image: BBC)

In his final scene, Charlie left in the passenger seat of a yellow car with a sign reading “just retired” on the back of the vehicle.

Derek announced his departure from Casualty in May last year as he confirmed: “The time has come for me to hang up Charlie’s scrubs.”

The actor, who had a five-word message for his dedicated fans, described his exit storyline as “some of the best episodes of my career”.

“How [Casualty writer] Michelle Lipton wrote these episodes comes across like she’s written eight plays, taken from so many points of view,” he added. “I don’t think there’s another writer who could have done it.”