You could hardly find a more enthusiastic fan of Frasier than me – starting when he was back in Boston and drinking at Cheers. And this is my second time seeing a Kelsey Grammer first night as I was fortunate enough when marooned in New York in 2010 during the ash cloud to sit beside ‘Niles’ for La Cage Aux Folles. And go to the after show party.

Even then, I thought he couldn’t really sing.

Remember the tag line from the closing credits of the TV series: Frasier has left the building? If he has any sense, he won’t be back.

Nothing can disguise the fact this is a vanity project of insufferable proportions which carries with it the question of which came first for the Grade/Linnit company – the misguided desire to mount an epic scale production of Man of La Mancha, a musical which hasn’t been.produced in London since 1968 for very good reasons, or the need to find a project for Grammer?

If the latter, they should have revived My Fair Lady – Grammer would have been a superlative Professor Higgins, the singing load is light, and he could have deployed his impeccable comic timing. Man of La Mancha is so dustily humourless he’s left with nothing but bluster, clumsy physical comedy and flat aphorisms either as the imprisoned poet Miguel Cervantes or his imaginary knight Don Quixote.

It’s too easy a pun, but he really is the Ham of La Mancha.

All Quixote’s relationships are creepy. He is more naively optimistic and blindly trusting than Candide, more prurient over a much younger woman than Mack for Mabel, and in an hoary old chunk of sidekick overacting with Peter Polycarpou, he has a more irrationally devoted servant than Norma Desmond does in Max.

Almost everything in this production is wrong – from the overdone polystyrene cave set that doesn’t fill the proscenium (and the worst staircase since Sunset Boulverard’s exhausting fire escape) to the officers of the Spanish Inquisition as threatening as the ones in the Monty Python sketch.

Despite the different gender politics of 17th Century Spain, there’s seat-shiftingly uncomfortable treatment of the rape scene: over-lit and over-long when it should be covered in shade, and a couple of bizarrely anomalous elements when the Duke looks like a cloned Lucius Malfoy, and the mirror knight does a sort of camp Darth Vader.

Hedging their bets in the ‘him off the telly casting’ with a star from this side of the pond, Grade/Linnit have engaged Nicholas Lyndurst – perpetually dubbed ‘Rodney’ from Only Fools and Horses despite being a much more varied and flexible actor. Here he’s tasked with a prison warden obliged to play a Thenardier-style innkeeper in a state of permanent inebriation which he manages to infuse with a touch of that campest of commandants, Herr Flick.

There’s a big loud band – although you sense it may not be as big or as grand as their previous productions like Sunset Boulevard and Sweeney Todd. But it also emphasises how weak and tedious is the score, and how often the one known tune repeats and repeats in your ear. Yes, that’s a Cole Porter lyric, but nobody’s going to remember many of Joe Darion‘s, who, with composer Mitch Leigh went on to well-deserved comparative obscurity.

Maybe we can still salvage My Fair Lady – get me Michael Grade on speed dial. Polycarpou would have fun and some decent lines as Colonel Pickering – even though he’s more plausibly EOKA separatist than Indian Army – Cassidy Janson would make a good Eliza, Julie Jupp a brilliant Mrs Pearce, Nicholas Lyndurst could return to his cockney roots as Alfred Doolittle and David Seadon-Young’s wonderful voice would so suit ‘On The Street Where You Live’

until 8 June.