Miller replaced “lorgnettes and lace” with the shabby filth of Gilray and Hogarth. He described his intention as one of producing a “bulging, warty vitality”.

But Cottrell says: “Standards of hygiene were not quite as low as that - people were a bit cleaner”. Tim Goodchild’s set is bright and creamy under oceans of Kevin Sleep’s lighting (in part at least because directional lighting is more difficult on a thrust stage where you have to light from 360 degrees). Goodchild festoons the stage with scandal-sheet headlines from 1777 to the present. No one’s granted a respite in the hurly-burly of juicy titbit collection.

Sheridan, says Cottrell, strongly disapproved of the scandal set but “One of the very real difficulties of the play is they’re so wonderfully expressed we want them back”. A useful rehearsal tool was substituting modern real-life names for those in the play, and Cottrell’s new prologue features a contemporary actress revelling in a tabloid until she finds her own name there.

Last year Cottrell directed The Rivals at Chichester. He finds a fascinating contrast. “The Rivals is entirely good-humoured, there’s not a malicious bone in its body and the characters couldn’t be anything other than English”. Many scenes, including the final one, are set in the open air. By contrast, School for Scandal (seen first at Sheffield’s Crucible) is all indoors, and is very urban. Unlike The Rivals it has a dark side, the world of Joseph, Lady Sneerwell and the scandalmongers, to set beside the light of Charles, Rowley and Oliver. Between these elements are the Teazles. “Lady Teazle is the only character who - I wouldn’t use the judgmental term reforms - but who changes. That’s why she’s important; it’s her play, about what happens to her. I suppose Sir Peter grows too but everyone else is delightfully, unhappily unchanged”.

One similarity with Sheridan’s other best known play is the famous screen scene, “one of the greatest bits of dramatic writing in English”.

Structurally, nestling in act four, it is the equivalent of the scene in The Rivals where Sir Anthony takes his son to visit Mrs Malaprop and Lydia. Each character realises in turn how Jack Absolute has been tricking them. As in the screen scene “there’s payoff after payoff after payoff, the release of a spring wound up over three acts”. As for the screen scene, “What’s so wonderful about it is, in some magical way - I suppose it’s because of the scene between Sir Peter and Charles - he makes you forget Lady Teazle’s there, even though you know, you still have a shock. At the same time as you laugh you’re aware of the consequences on Lady Teazle and Sir Peter. Even in rehearsal, hearts stopped at the moment of silence as she is revealed”.

We focus less on Joseph, he thinks, because we know his character is going to be exploded. And the reason we focus more on Lady Teazle’s predicament than asking how she will try to get out of it is because she has already said No to Joseph before it became necessary for her to hide. This makes for an interest in character rather than comic plotting.

On the dark side, Lady Sneerwell is “a bit underwritten. A very interesting character. We know more of her than any other scandalmonger because of what she tells Snake. She’s a figure recurrent in plays of 80 or 90 years earlier, the wronged lady of Restoration comedies. Sheridan must have intended sympathy, or understanding, in telling us so much about her. I’ve sympathised with her because it’s very sad to have that hopeless passion for Charles. And he gives her a wonderful exit line”.

Richard Garnett plays Joseph. “I’ve never seen a Joseph before who’s actually funny. So he turns into one of those Iago-like characters. We know we ought to condemn but can’t because he talks to us all the time. The plus side of that is; because as Joseph you’ve told the audience how ghastly you are, you don’t have to be anything other than charming to the characters in the play.”

Until September 14. Tickets: 01243 787288. Runs 2 hrs 45 mins.