Holby City will welcome back two classic characters next year as part of its 20th anniversary celebrations.
The medical drama, which premiered in January 1999 as a spin-off to Casualty, will mark two decades across the whole of next year, rolling through to the landmark 1,000th episode in the autumn.
Sharon D Clarke will reprise her role as Dr Lola Griffin to hold a mirror up to her ex-husband Ric Griffin (Hugh Quarshie) in one episode that will reflect on his years at Holby.
Clarke played the character from 2005 until her departure in 2008.
Denis Lawson will return for two episodes as cardiothoracic consultant Tom Campbell-Gore, after appearing in Holby City between 2002 and 2004.
Having spent years working on rebuilding his reputation since leaving Holby City Hospital, Tom returns to meet former rival Ric, against whom he must compete to win vital funding at a conference.
Clarke said, of her return to Holby City: “I spent three and a half happy years playing Lola. She was the kind of woman I would have loved to have seen on my screen when I was growing up.
“I was very proud to bring her to life and be a part of the Holby family. I’m so excited to be treading the wards again, and seeing what Lola will be getting up to for Holby’s 20th anniversary. Hey Ric, Lola’s back in town!”
Lawson said: “I have great memories of my time on Holby City and I’m delighted to be back on my old stomping ground with the Holby cast and crew.”
Simon Harper, executive producer of Holby City and Casualty, said: “It’s so exciting to celebrate the continued success of Holby City – one of the UK’s most beloved medical dramas.
“It’s a massive thrill to have Denis back, not only as one of our country’s foremost actors but also as one of Holby’s original bad boys in the show’s early years. Tom Campbell-Gore hasn’t changed a bit since he left Holby 15 years ago and definitely has some scores to settle with Ric.
“And it’s such a coup to have Sharon here again too, it’s fantastic too given how in-demand she is – not only is she a fabulous actor and a much-loved, tender, funny Holby character but we clearly couldn’t let the anniversary pass without the appearance of one of Ric’s many ex-wives to ruffle his feathers.”
Mr Harper said the 1,000th episode will take place around Bonfire Night, and fans can expect “an explosive story”.
More details on Holby City’s 20th anniversary year will be announced in due course, the BBC said.