A 1979 television comedy-drama about a group of people trying to pass The Knowledge has been adapted for the stage by Simon Block, and is directed by Maureen Lipman

Black cab drivers are astonishing people and driving skills are the least of their talents. They carry in their heads detailed knowledge of every street in London, daily adding new information about diversions, one-way streets and changes, temporary or permanent. In addition, they need to understand and tolerate their passengers, drunk or sober. However do they do it? No wonder they have developed brains in which the hippocampus is much larger than normal.

Back in 1979, Jack Rosenthal wrote a television comedy-drama about a group of people trying to pass The Knowledge. It’s now been adapted for the stage by Simon Block, who has retained much of the original – very funny – dialogue and characters, and directed in spirited fashion by Rosenthal’s widow Maureen Lipman.

TV drama tends to call for rapid scene-changes, which can be confusing in the theatre, but Nicholai Hart-Hanson’s composite set, geometrical and brightly-coloured,rather like a Mondrian painting, solves this problem ingeniously. Combined with lighting by Leigh Porter, it offers an ever-changing backdrop for entertaining and moving performances by a talented cast.

On opening night. the authenticity and entertainment value of Rosenthal’s piece was confirmed by the enthusiastic appreciation of numerous cab drivers.

Although still largely relevant today the individual and social attitudes are firmly grounded in 1979. There is gentleness in the humour, rare in our harsher age, and the dialogue is funny but never cruel. Of central importance is the eccentric, merciless and occasionally comic Mr Burgess, the all-powerful examiner. Played by Steven Pacey, he makes this larger-than-life character credible, even vulnerable.

The lives and attitudes of the applicants, and their partners, are each altered by the experience of gaining The Knowledge. Only two achieve the coveted green badge: Chris, the young, unmotivated dropout who becomes positive, even ambitious, is convincingly played by Fabian Frankel, and the only woman, Miss Staveley (Louise Callaghan), who gains the independence she so desires.

A question remains that this period piece cannot address, what is the future for black cabs? London has never been more congested, polluted, or impossible to navigate. As to the threats imposed by Uber, sat nav and diesel fumes, who can say?

4/5 stars