Very importantly, this is not simply a production of Oscar Wilde’s comic masterpiece and most perfect of plays. It is a play about a bunch of middle-aged (and older) amateur actors somewhere in twee middle England putting on their latest staging of Oscar’s comic masterpiece.

I wish the West End’s Harold Pinter Theatre had communicated this in advance, and this play really ought to be called something else. With lots of new (and often lame) material written by Simon Brett, it is a different proposition entirely.

Accomplished director Lucy Bailey and her star cast (for a certain generation) might argue that these layers of pretence are worthy of the great man Wilde himself, but I was profoundly disappointed to discover they had meddled with the script.

Amusing contemporary references to things like mobile phones, test match cricket on TV, Nike trainers and Fifty Shades of Grey simply got on my by-now already frayed nerves.

Most annoying is that the new lines and scenes disrupt the original plot’s ideal flow and architecture, not to mention wrecking the comic timing of Wilde’s beautifully-crafted one-liners. I understand that the ever-youthful Nigel Havers (aged 62) as Algy, Martin Jarvis as John Worthing, and the rest of the cast are pretending to be amateur players, but this jokey premise doesn’t excuse poorly-delivered lines, nor their irritating messing about on stage.

Siân Phillips’ enjoyable Lady Bracknell is sadly not enough to redeem a production whose very concept is flawed. Modern interpretations of classic old plays can be some of the most rewarding experiences of going to the theatre. But versions that re-write and embellish works of genius do so at their peril.