Writer Frank Norman couldn’t spell. Composer Lionel Bart had no facility with musical notation.

Yet these two precocious talents combined in 1959 in creating Fings Ain’t Wot They Used T’Be now in revival at the Theatre Royal under the direction of Terry Johnson.

Frank Norman has largely been forgotten as a writer and his books are no longer in print. That’s sad because today much of the performance and musical landscape has been hijacked by the privileged classes as instanced by the likes of Damian Lewis, Benedict Cumberbatch, the Mumfords and James Blunt.

Fings is a palpable reminder of the vibrancy of the working-class theatre pioneered by Joan Litttlewood and her generation of performers and writers.

The esoteric communities and individuals that characterised mid-20th century Soho — the locale of the show — is giving way to bleak and bland corporate invasions. Fings certainly ain’t what they used t’be and it’s a bloody shame but, then again, neither is nostalgia.

This production, evocatively set by William Dudley in a seedy subterranean bar reminiscent of the long departed Ward’s Irish Bar in Piccadilly, is inhabited by a motley collection of spivs, pimps, petty larcenists and prostitutes. They’re presided over by ex-con Fred Cochran (Mark Arden) and his lady companion Lil (Jessie Wallace).

The plot, such as it is, concerns Cochran’s attempts to reassert his authority as head Soho honcho and to see off a challenge from the menacing yet unseen rival upstart Meatface.

Running in parallel is the tale of Rosie (Sarah Middleton) fleeing domestic violence and now being inducted into a life of prostitution by Tosher the pimp (Stefan Booth).

Add to this mix bent copper PC Collins (Gary Kemp), sundry prostitutes and low-lifes and you have a show that Littlewood compared to Guys And Dolls with its flies undone.

There are certainly echoes here of Damon Runyon but also of Charles Dickens and a passing glimpse of Bertold Brecht.

The narrative is wholly incidental, though. The joy of this production is the parade of rum characters expressing themselves in a series of well-choreographed musical set pieces and songs.

Stand-out numbers are the plaintive renditions by Rosie in Where Do the Little Birds Go and Sparrows Can’t Sing and, of the ensemble pieces, Cochran Will Return and Meatface.

The signature tune Fings Ain’t Wot They Used T’Be is a reminder of Bart’s talent in combining simple tunes with a lyrical virtuosity to create accessible songs that belie their verbal sophistication.

All members of the cast perform brilliantly but the show is stolen by Christopher Ryan, who has the best comic moments as petty thief and serial stammerer Red Hot, and Suzie Chard as the big tart with a bigger heart and much else besides.

Musical direction by Elliot Davis is simply sublime.

Runs until June 8. Box office: (020) 8534-0310.