IT initially started as a spin-off to perennial favourite Casualty.
But Holby City has itself become a long-running phenomenon and 2019 sees it mark its 20th anniversary.
The London-filmed hospital drama is one of BBC 1’s staples and a couple of Scots are among those featuring in its big year – new recruit Dawn Steele and returning Denis Lawson.
Catherine Russell, who plays surgeon Serena Campbell, reckons she can put her finger on some of the elements that have made it such a success story.
“I think people like the regular cast that they get invested in,” Catherine told iN10. “That’s kind of soapy but, on the other side, there’s real serious medicine.
“Obviously, it’s fiction and you have to begin and end a story within an hour – so someone will come in with chest pains, have major heart surgery and then be sitting up and having a chat and a cuppa.
“But it’s all so well researched and we have nurses on set every day. When there’s an operation we have a real surgeon on hand and they always say that the prosthetics are extraordinary.
“They say they are exactly like the real thing. Then we have great guest artists who help to mix it up for us and keep it fresh.”
Catherine, 53, who admits the surgical scenes are still a real challenge, joined back in January of 2012 and says she couldn’t have imagined it would turn into such a long-running commitment.
“I’d only ever done one job for a year before that, which was Mamma Mia! in the West End.
“I know it might sound weird to anybody that’s not in this business, but I had always been anxious about signing up to something for a long time.
“One of the joys of being an actor is that you don’t know what’s round the corner, so I was very nervous about even signing on for a year but it went so fast and was so much fun I found myself staying.”
However, in 2017 Catherine decided she needed a break and show bosses agreed to write her out for a while but to allow for her return.
“Having that time away completely reset my batteries,” she said.
“It wasn’t that I was bored playing Serena it was just that there is a bit of a conveyor belt quality to it.
“You’ve just finished one script and another three land on your doorstep. So you’re constantly carrying around anything from two to six story lines in your head. It was that, not the character or people, I felt like I needed a break from.”
The nine-month break in 2017 allowed her to appear in a play and treading the boards again after a long period away tested her nerves.
“It was terrifying!” she laughed. “If you make a mistake during filming you have the luxury of doing it again.
“I had forgotten how frightening it is standing in front of an audience but it’s also such a thrill when you’re doing comedy and you hear them laugh.
“It was very different from working on Holby and it was great to go back to the stage.”
But it wasn’t all work for Catherine. She went travelling around Europe in a camper van with her husband, film producer Richard Holmes.
It was an extensive trip that saw them clock up 16 different countries in three months.
“We were initially going to go to America,” said Catherine. “Then Brexit happened and we thought we’d better do Europe while we still could before you needed a visa for every border.
“It was extraordinary, truly the trip of a lifetime and only really possible because I had the luxury of knowing I was coming back to a job.
“And I’m happy to drive anywhere now after negotiating some of the hairpin bends in Italy, Switzerland and Austria. I loved the Baltic states, which were a real revelation to me.”
Catherine says they found the welcome universally warm, although the UK’s impending exit from the EU was a constant source of comment.
“People weren’t just interested, they felt worried and terribly sorry for us.
“It was the first thing they wanted to talk about.”
Holby City, Tue, 10.45pm, BBC1 Scotland (8pm, England and NI)