http://www.imdb.com/title/tt0731959/...nm_flmg_act_18
In this episode, Peter Gunn plays Sidney Snell.
There's a scene between David Jason and Susannah Doyle. They're walking up the stairs in their nick. Between them they diagnose a man on the basis of his having sex or not. Like sticking his penis in a woman would qualify him as an adult.
I really like Frost, or "A Touch Of Frost", but I think this summary condemnation, of a child trapped in childhood is wrong.