Actor Olly Rix, previously known for his role as Matthew in Call the Midwife, is set to make a dramatic career shift as he joins the BBC medical drama Casualty.

In the new 12-part miniseries, Internal Affairs, Olly will trade in his sharp suits for medical scrubs, taking on the role of Flynn Byron, a bold and unconventional Clinical Lead.

The series, which begins on Saturday, March 15, will be available on BBC iPlayer from 6:00 AM and on BBC One at 8:30 PM.

The first episode, told from a patient's perspective, introduces Olly's character alongside guest star Robert Bathurst, known for his roles in Downton Abbey, Cold Feet, and Doctor Who, who plays seasoned surgeon Russell Whitelaw.

The episode's synopsis reads: "As the new Clinical Lead Consultant at Holby City ED, Flynn joins the NHS fresh from a tour of duty.

"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."

Olly expressed his excitement about joining the show, saying: "It's been a pleasure to join the Casualty cast in such a dynamic role," reports .

"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."

Olly is best known for his role as Matthew in Call the Midwife, where he starred alongside Helen George, who played his wife Trixie.

His character made his debut in series 10 but bid farewell to the show at the end of series 13. However, there were hints that Olly might make a comeback.

Earlier this year, Helen confessed to Radio Times that she was unsure about Olly's return to the popular BBC series.

She said: "Who knows! 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."

Casualty returns to screens on Saturday, March 15 at 8:30pm on BBC One