Former Taggart favourite John signed up as consultant Guy Self immediately after bowing out of Coronation Street as killer barman Karl.
And he’s told the Sunday Post he thought he’d be getting itchy feet by now.
“I’ve been here two and a half years and three years is a good amount of time to be in a show like this,” said John.
“But it’s a great character and there’s more to be got from him.
“I’m not bored yet so I’m happy to do some more.
“He’s the most powerful character I’ve ever played. He’s a world leader in his field but he’s got this complex private life.
“He doesn’t know how to operate with people on a personal level but as soon as it’s medicine then, bang, he’s in there.
“He’s a slightly tragic character who brings about his own downfall. He had a brief relationship with Rosie Marcel’s character Jac Naylor and I’d like to see if he resumes that and what happens next.”
There’s a real medical background in John’s family, with his sister having been in nursing and his brother-in-law a doctor.
And the show’s portrayal of hospital life gets the thumbs up from one of his old Edinburgh University pals.
“He’s a consultant down here now,” explains London-based John.
“There are a lot of politics and power games involved in running a big NHS hospital and he says it’s all very true.
“Although this is a TV drama, you realise how important every single person’s job is, from the cleaner to the consultants and head honchos in management.
“They are all essential and their jobs should be prized and respected. It opens your eyes to why the NHS is an extraordinary institution.”
John admits Guy’s deep thinking and deep plotting is a world away from Corrie’s Karl or Taggart copper Robbie Ross.
“Robbie used to just think on his feet and then go for a drink,” he laughs. John spent years in Glasgow filming Taggart and then was up and down to Manchester during his Corrie days.
Now he’s not on the plane or train, he’s savouring what he calls “some me-time” along with wife Carol.
“I like to run – or it’s better described as jogging these days – and get to the gym and swim.
“You get to do more of the nice stuff and see the family every day, although my wife’s probably sick of that now!”
While Holby’s still one of the BBC’s most popular long-running dramas, John confesses he’s enjoyed the slightly lower profile after soap life.
And he doesn’t miss the madness surrounding all things Weatherfield.
“There were some mad fans who feel they have the right to manhandle you and position you for photographs.
“It could be pretty mental, especially when people had had a drink.”
He still gets fan-mail from people of all ages but, remarkably, John turns 60 this year.
He says it’s just a number and that being in good health is definitely the most important thing but he confides that he has no big celebration planned.
“I think I might just let this one slip quietly by.
“I actually had a big one for my 50th. I was doing Taggart at the time and all my family got together in Glasgow.
“I was away so much at the time it was nice for Carol and the kids to all be there.”
Scotland still has a big pull for John who was in the stands at Murrayfield for the Scotland vs England Six Nations rugby match last week.
And he’ll be back up in March having signed up to shoot a horror comedy that Greg Hemphill is making, which is set on an island lighthouse.
“I asked Holby if there was any chance of a few days away and they very kindly gave me 10 days to do it,” adds John. “It was really good of them and I can’t wait to get up and spend time around the west coast.”
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