Unpleasant individuals who boss other people about while convinced they are acting in the best interests of society are neatly skewered by Alan Ayckbourn in Neighbourhood Watch.

The master dramatist’s 75th full-length play — which he is also directing — finds him in more-than-usually sombre mood as he shows us a horribly credible group of middle-class zealots fighting to protect their corner of England from the barbarians they believe to be battering at the gates.

Hannah Arendt’s memorable phrase “the banality of evil” slips easily into the mind as we watch these odious misfits work up their bureaucracy of oppression on their high-fenced housing estate. Features of it include a discipline and punishment sub-committee to decide who shall occupy the stocks.

Over-the-top though this allegorical tale clearly is, one notes the useful lesson about personal freedom that it gives. It will not delight all, however, since a pair of devout Christians are the principal oppressors.

These are brother and sister Hilda (Alexandra Mathie) and Martin (Matthew Cottle) whom we meet as they are preparing to welcome their neighbours to a housewarming party at their new home.

Actually, we meet Hilda even earlier, delivering the address at the opening of a memorial garden commemorating the late Martin. Though Ayckbourn has penned a programme note berating critics for giving plots away, he curiously chooses to reveal one of the crucial details of this one, viz. that the principal character is soon going to die. The reason for the disclosure eludes me.

Of the pair, Hilda — for all her “I’m mad, me” faux jollity — is the more terrifying of the two. Their mother having died young, she has filled the maternal role in her brother’s life and clearly resents it when, as here, he starts to stray from the path she has planned for him.

Her particular spite is reserved for flighty neighbour Amy (Frances Grey) who has rather freer ideas than she about sexual morality. Tarring and feathering is the punishment she recommends to her cuckolded husband, overwrought Welsh do-it-your-selfer Gareth (Richard Derrington). He embraces the idea with enthusiasm. One feels sure, too, that such a course would find favour with other members of the watch, including the garrulous doommonger Rod (Terence Booth) and the Daily Mail reading ‘journalist’ (actually small ad salesperson) Dorothy (Eileen Battye).

The only character who recognises the madness for what it is is neighbour Luther (Phil Cheadle), who is dismissed as a Guardian-reading lefty by the others. The position of his music-teacher wife Magda (Amy Loughton) appears more equivocal, until an eye-opening revelation — a typically Ayckbournian surprise — at the close of this slightly overlong but always enjoyable play.

Until Saturday. Box office: 01865 305305 (www.oxfordplayhouse.com).