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.
David Jason grew a mustache 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 mustache 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.
Novellist R.D. Wingfield, whose "Frost" book were the inspiration for the series, was very critical of the TV adaptation and said that it had ruined the character of Jack Frost that he had created in his novels.
Between takes, the cast (particularly David Jason) and crew were forever playing pranks on John Lyons (DS George Toolan). They devised fake scripts which Lyons had to learn at short notice, involving ludicrous situations for Toolan: on one occasion, they made his character wear a neck brace; on another, they made him ferret around in a smelly rubbish bin looking for evidence. Each time, Lyons said "You won't catch me out like that again" but he always fell for the next prank.
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.
Two of the regular stars in this series are actors who have changed their names from White for professional reasons. Inspector Frost is played by David Jason (real name David John White) and his on/off girlfriend Shirley Fisher is played by Lindy Whiteford (real name Lindy White).
To prevent the show from becoming too formulaic, Frost had several sidekicks between cases, unlike most detective shows. It gave him new characters to bounce off and challenge his slightly set view of the world.
David Jason said Frost was a man who passed from his fifties deep into his sixties during the course of the show, and wasn't likely to be knocking his pipe out until four in the morning. He figured it was better to put his head in a paint pot for a couple of hours and wind down that way.
David Jason said the popularity of the show was based on a hunch that had well and truly paid off. He liked the darkness of the show after the lightness of Only Fools and Horses.... (1981) and The Darling Buds of May (1991) because it showed audiences he could play both, but lightness became a part of Frost too.
Of all the shows David Jason has done, he claimed this was the one that involved the most elaborate mucking about on the part of the people involved in it. The other show that ran a close second was Only Fools and Horses.... (1981).
David Jason liked launching rockets while making the show; sometimes to great acclaim, sometimes not. He liked to build ships and planes which then developed into rockets and then launchable rockets between two and five feet tall, with an engine and an explosive component that could fly between 500 and 900ft in the air; Jason liked the rockets best because you could get a performance out of them. Jason assembled them with tools packed in an old makeup case and from specialist parts from obscure sources across Yorkshire. Jason launched them for cast and crew at the back of Leeds Hospital for three years when they filmed in the mortuary. Jason later built a launch pad from an old lighting stand and added a launcher with a key, lights and a 2-tone alarm. They were the dampest thing you had ever seen. The masterpiece was a Saturn V replica with one of the biggest engines so it was a complex build. It launched like the real thing by hovering above the pad and set off into the sky. Jason liked launching that one most, especially when they came back, which was never a sure thing, with a parachute that emerged from the nose cone. After constant use, it failed to launch at all, and was reluctantly retired.
David Jason said he never would have been cast as Detective Inspector Jack Frost if he hadn't appeared in A Bit of a Do (1989) first, because it put him on Yorkshire Television's radar, which subsequently led him to The Darling Buds of May (1991) and than Frost.
When The Darling Buds of May (1991) came to an end, David Jason was asked what he wanted to do next, a new and exciting experience for him, because his television career had gotten so successful he could shout the odds on where his career went. He said he loved detective shows, and wanted to play a detective, which culminated in him getting the role of Detective Inspector Jack Frost.
When David Jason expressed an interest in playing a detective, five books, all crime fictions in different areas by different authors were posted to him. Jason took them on holiday to Florida and read them over the next fortnight by the pool. Before Jason settled on Detective Inspector Jack Frost, he considered a Sherlock Holmes type detective because it was different from anything else he had done. Jason called from Florida saying he wanted Frost.
David Jason said the show was "contemporary, clever, dark and revolved around unpleasantness like murders of drug addicts and robberies at strip clubs". Also, Frost was "shabby, bitter, caustic and a commanding character, unlike Pop Larkin".
Frost had to be cleaned up from the books, where Frost was a chain smoker, but David Jason recently gave up smoking. He used to smoke four or five cigarettes a day, or in the evening with a drink, and didn't want to start again, and smoking was taboo on TV in 1992. Frost was made a former heavy smoker who had just quit, making him grumpy and irritable around people who still did.
During the wrap party for The Darling Buds of May (1991), David Jason was asked by Yorkshire Television executives why he thought he could play Detective Inspector Jack Frost in the upcoming series. Jason felt he was being interrogated by good and bad executives. He explained the genre was very popular, and he wanted to explore a slightly darker edge in the character of Frost, while claiming the superiority of English detective shows (audience attempts to solve crime in tandem with the detective) to the American attempt (audience is shown the crime and the criminal at the start of the story, and then follows the detective's trail to the guilty party). After that, Jason had convinced them.
There was a courtroom spin-off considered called "The Usher" but within three months of the end of the show, Yorkshire Television changed hands and amalgamated with ITV, so "The Usher" never went ahead.
In September, 2008 a press release went out about Jack Frost's retirement. Not because of lack of storylines or David Jason losing interest in the character (he would have happily played him forever), the problem was Jason's age: at 68, Jack Frost was the oldest copper on the force. He would have retired ten years before or sooner, so he bowed out spectacularly, according to Jason.
Like The Darling Buds of May (1991), both shows had a tough food regime that was hard on David Jason's stomach, because Frost wasn't a healthy eater, e.g. bacon sandwiches, chips, fry-ups, etc. People used to remark on it to Jason, that he was eating badly.