Frances de la Tour (left) as Dorothy, Linda Bassett as Iris – the real stories behind the Trust’s grand homes

There is no small measure of comedy in watching one National Treasure taking a shot at another. Playwright Alan Bennett (of History Boys fame) could well be considered one of Britain’s National Treasures, with his uncanny ability to capture the essence of the English. And one of their favourite pastimes is to visit National Trust properties, and see how the other half lived. I would hazard a guess that at least three quarters of the National Theatre audience on any given night of this sold-out run were also members of the Trust. The vicious asides about the rapacious greed and lack of morals displayed by the Trust triggered waves of shocked giggles.

Bennett’s witty banter doesn’t hide the fact that this is a sad indictment of how our society has become obsessed with money. Everything, no matter how sacred, has its price. In his unholy triumvirate, the church, the Trust and the sex trade, it is the latter that is shown to be the most humane and compassionate and yes, honest.

We meet two old bats, Dorothy and Iris, holed up in an icy once palatial setting, deciding whether to oppose the plans for their family home to be sold off to the National Trust. They look as if they have just come in from the local homeless shelter. A wily financial assessor tempts them with the prospect of untold riches if they favour his nameless rich clients, setting off a chain reaction that shows just how ugly things can get. The other sister June is appalled when she finds that Dorothy has allowed a former flame to shoot what the audience is quick to grasp is a porn movie, while the two old biddies are ostensibly unaware. All they see are kind people, who fix the hot water and the heating, arrange a good scrub and pull out of the cupboards ball gowns that reveal a heady past of wealth and prestige.

The tussle between the sisters becomes almost unbearable, with the younger, more vigorous June, herself a lady of the cloth, expressing the desire to give back to society what her family took from it, but accused of only developing these sentiments once she learned she didn’t stand to inherit herself. Bennett exposes the voyeurism of nosing around the homes of others, and equates the salaciousness of finding the real stories behind these grand homes with an excess worse than pornography. With unerring bite, the vicar finds true accord with the money man when discussing the possibility of a celebrity Eucharist. From that point, Dorothy’s fate is sealed, but the playwright ensures that the next time you meet a landowner fallen on hard times, there will be more compassion in their humiliation at the hands of the masses.

The cast, headed by Frances de la Tour, are superb. De la Tour has been in almost every one of Bennett’s plays, and she delivers his acerbic prose with impeccably caustic timing. She is matched by the other leads, Linda Bassett (East is East) as Iris and Selina Cadell as June. The males in the ensemble are also wonderful, particularly Peter Egan as the oily Mr Theodore.

Structurally I found the play’s great reveal, when the Adams ceiling is restored to its former glory, an awkward device to show off the technical wizardry of the National’s stage, but certainly it made the before and after of the setting sharply etched visually. Designer Bob Crowley has great fun with the extremes of the set and costumes, with Dorothy flaunting some gorgeous frocks from yesteryear. Director Nicholas Hytner, another old hand with Bennett, is in form with this one.

There is comedy here, it is true, but the playwright cynically allows the ancient prayer beads to be cast aside as glass trinkets. While everything can be commercialised, priceless gems are valueless. History is simply an untrustworthy version of what the highest bidder chooses to espouse. It’s a bleak vision of today’s society that Bennett gives us, and although much of what he says holds true around the world, perhaps the peculiar obsession with other people’s houses is so particular to the British that this may be a play that doesn’t travel very well.

A scene from People – centre stage Linda Bassett as Iris, Frances de la Tour as Dorothy (centre) and Selina Cadell as June