Frost was a chain smoker in the novels. In his 2013 autobiography "My Life" David Jason revealed they decided to make Frost a non-smoker in the television series as he had recently quit smoking cigarettes in real life.
In a 2008 interview David Jason admitted he had to stop playing Frost because he was too old to play a policeman.
Arthur White, who plays Ernie Trigg, is David Jason's real life elder brother. There was already an actor called David White registered with the acting union so David chose to use Jason as his stage name.
David Jason grew a moustache for the role. It was his idea, as he imagined Frost grew one in his youth to give himself a few extra years and more maturity. He lost the moustache between series to play other parts and than needed four weeks to grow it back as well as stop shaving at the right time ahead of shooting. Sometimes Jason missed the mark and had to help it along with a bit of "coloring-in"' but it was always ready for filming.
Filming meant spending a lot of time away from home, at the studios in Leeds or on location in Wetherby, Harrogate, Dewsbury and all local stations. Yorkshire Television made it easy on David Jason by renting out a cottage rather than pay for a hotel, especially since Jason could cook for himself; he just wanted somewhere simple to go at the end of the day to clear his head. Yorkshire Television found Jason an old farmer's cottage without central heating, so he had to light a fire; on warm evenings he sat out in the garden which was always a pleasure. When asked did he get lonely, he said he didn't, because he enjoyed the quiet time. He also had his own driver, on call 24hrs a day, who collected Jason from Buckinghamshire for the 3hr drive to Yorkshire while he worked on his scripts, stop along the way for a bacon and egg roll and a cup of tea ("a very Frost-like meal"). Jason lived in a spartan farm cottage while the cast of Frost stayed at a hotel.