Robin appeared in a number of film and television roles before two key appearances in 1973. The first was in appearing in Antony Balch's Horror Hospital. Now seen as something of a cult film, it is in many ways a bizarre hybrid of horror and the mild titillation of the later 'Confessions...' films. In the same year Askwith also appeared in a Carry On film, Carry On Girls. These appearances led producers Norman Cohen, Greg Smith and Michael Klinger to offer him the starring role in Confessions of a Window Cleaner after the part was turned down by several other previous candidates, Richard Beckinsale, Richard O'Sullivan, Nicky Henson and Dennis Waterman. The success of the film led to three sequels, Confessions of a Pop Performer, Confessions of a Driving Instructor and Confessions from a Holiday Camp.
Although the Confessions series came to an end with Confessions from a Holiday Camp, a fifth and a sixth film, Confessions of a Plumber’s Mate and Confessions of a Private Soldier had been planned in 1977. Askwith even expressed a desire to direct Private Soldier, but neither film materialised. Plans to shoot a further made-for-video Confessions film in the 1980s also came to nothing, although by this time he was appearing in the ITV sitcom Bottle Boys.