This is a musical that has barely been seen since its first outing in the heady air of 1963, when it formed an all-singing all-dancing vehicle for the irrepressible Tommy Steele. And the clue to the difficulties of its revival is there in the title: half of an obsolete currency doesn't add up to very much.

But the impresario Cameron Mackintosh had a fondness for this "story of a simple soul" based on a semi-autobiographical novel by HG Wells and so he assembled the team that transferred Mary Poppins so successfully from screen to stage - book writer Julian Fellowes and composers and lyricists George Stiles and Anthony Drewe - to give it a new lease of life.

They do their best, with seven new songs and substantial revisions of David Heneker's originals, but there is nothing they can do to save the musical from being terminally old-fashioned. There is a huge amount of hustle but not much heart in this tale of 'umble young Arthur Kipps, who is elevated from his job in a draper's shop when he comes into a fortune - and loses both the girl who loves him and his bearings in the process. It is simply hard to care about anything that is going on.

That's not the fault of Rachel Kavanaugh's energetic and stylish production which, with the help of Paul Brown's attractive set based in a revolving bandstand, and Luke Halls' video projections, moves smoothly from place to place, from Edwardian high society to the warmth of the pub, as the story unfolds. Andrew Wright's choreography is terrific lending real oomph and flair to the big set piece numbers - particularly the climactic "Flash, Bang, Wallop!" and a new number where Kipps leads the upper classes in a banjo knees-up, which ends with one chap swinging from the chandelier.

What's more Charlie Stemp, young and fresh-faced, is a real find as Kipps. He is an attractive personality and a fantastic dancer, with high jumps and sharp pirouettes, and a nice line in a soft-shoe shuffle. He's ably backed by a cast giving it their all, with Ian Bartholomew and Vivien Parry in particular squeezing every bit of humour out of their stock roles as an eccentric playwright and avaricious mother respectively.

Fellowes gives the story his best Downton Abbey style class consciousness, and the songs by Stiles and Drewe are never less than pleasant and sometimes really witty. With their help, the slim story just about staggers to the interval, but by the second half it seems to starve to death. There is just not enough for the big numbers to feed on as Kipps agonises between working class Ann (Devon-Elise Johnson) and posh Helen (Emma Williams).

In the end, he loses his money but wins his girl - and perhaps that's the problem. Underneath all the fake good cheer, the rather unattractive moral of the musical is that people should know their place. Its jaunty smile hides a sour reality - and it is hard to go out into the night singing.

Half a Sixpence runs at Chichester Festival Theatre until 3 September.