Olly Rix will make his debut in the BBC medical drama Casualty on Saturday – and his character is worlds away from Call the Midwife’s Matthew.

While viewers are used to seeing Olly donning suave suits to play the 1960s businessman in the popular period drama, he’ll be swapping his pinstripe blazers for blue medical scrubs in the upcoming 12-part Casualty miniseries, Internal Affairs.

© BBC STUDIOS

The new drama begins on Saturday 15 March and will be available at 6.00am on BBC iPlayer and 8.30pm on BBC One. The first episode is told from a patient’s point of view and sees Olly play maverick Clinical Lead, Flynn Byron.

He’ll be joined by Robert Bathurst, known for his roles in Downton Abbey, Cold Feet and Doctor Who, who is guest-starring as Russell Whitelaw, a top-tier surgeon who has commanded the operating room for years with his unmatched skill and domineering personality.

© BBC STUDIOS

So, what can fans expect?

The synopsis reads: “As the new Clinical Lead Consultant at Holby City ED, Flynn joins the NHS fresh from a tour of duty. He’s a man with a purpose, and with a fierce resolve to make a difference.

“He faces the challenge of instilling change in a system weighed down by bureaucracy, all the while grappling with the trauma he has experienced and a deception that threatens to be his undoing.”

© Neal Street Productions/Andrea Southam

On joining the show, Olly, 40, previously said: “It’s been a pleasure to join the Casualty cast in such a dynamic role.

“Flynn crashes into the world of it from a very different background, resulting in a complex and exciting story in Internal Affairs and beyond. It’s a brilliant new chapter for the show and I am excited for the audience to get to know Flynn.”

The actor is best known for his role in Call the Midwife, in which he played the on-screen husband of Helen George’s character, Trixie.

© Neal Street Productions/Olly Coutrney

His character was introduced in series 10 but left Poplar for New York at the end of series 13. At the time, it was understood that the door was being left open for Olly.

Helen, who has starred in the drama since series one, revealed she doesn’t know what’s in store for Matthew. “Who knows!” she told the Radio Times in January. “It’ll be interesting to see what happens there. At the moment, I don’t know, and I’m excited to find out what happens.”