Fiona Gillies was the producers' first choice to play Clare Shearer when the character was introduced in 1997. However, she was expecting a baby at the time and so was unable to accept the role, which instead went to Yolanda Vazquez. When Vasquez decided to leave at the end of the 1997 series, the producers debated whether to kill off her character, but instead they approached Fiona Gillies. This time she was free to take over the role.
Originally Larry Lamb was due to join the regular cast in Series 4 (1996), playing Dr Richard Carey, with Jane Wymark playing his wife. However their characters were dropped after four episodes had been filmed; some scenes in those episodes had to be edited or re-shot. New producer Richard Handford left abruptly and Michele Buck (producer of earlier series) was asked to return.
When the scriptwriters wrote the cliffhanger ending to Series 12, in which Alex and Claire fell (presumably to their deaths) over the side of a quarry, they expected that there would be another series. However the producers subsequently decided not to make another series feeling that Peak Practice had outlived its usefulness and leaving the fate of these two characters forever unknown.
In Series 5, Will and Kate's baby, Emily, is treated at a cystic fibrosis unit in Bristol which is named after Vanessa Machin, a cystic fibrosis sufferer (played by Susannah Corbett) who appears in episode "Peak Practice: Other Lives (#3.15)" (1995).
The house in Wessington which was used as the location for David and Clare Shearer's house was actually owned by Dr. Tim Parkin, the medical advisor to the programme.