As of 2021, which of these British TV medical dramas has been running the longest?

'Casualty' is a British medical drama series that airs weekly on BBC One. Created by Jeremy Brock and Paul Unwin, it was first broadcast in the United Kingdom on BBC One on 6 September 1986. The original producer was Geraint Morris. Having been broadcast weekly since 1986, 'Casualty' is the longest-running medical drama series in the world.

The programme is set in the fictional Holby City Hospital and focuses on the staff and patients of the hospital's Accident and Emergency (A&E) Department. The show has strong ties to its sister programme 'Holby City', which began as a spin-off series from 'Casualty' in 1999, set in the same hospital.

'Doctors' is a British medical soap opera which began broadcasting on BBC One on 26 March 2000. Set in the fictional West Midlands town of Letherbridge, the soap follows the lives of the staff of both an NHS doctor's surgery and a university campus surgery, as well as the lives of their families and friends.

'Call the Midwife' is a BBC period drama series about a group of nurse midwives working in the East End of London in the late 1950s and 1960s. The first series, set in 1957, premiered in the United Kingdom on 15 January 2012.