I first saw Salad Days on its post-West End tour at the Theatre Royal, Exeter in 1960. Julian Slade played one of the pianos and I remember thinking, as a schoolboy, how this tuneful and slightly mad show was not at all as naive and innocent as I had been led to expect. So it proves, once again, but more so, at the Riverside Studios. Salad Days takes a gently subversive look at the society of its time and prefigures how music itself can unsettle and transform the people within it.

It is summer 1954 and Timothy and Jane, newly graduated from university, meet by chance in a park. There they meet a tramp with a magic piano. The piano, Minnie, not only transforms their lives with music which makes them dance, but also all those who happen to be within hearing distance.

It is easy to forget how suburban parks were once a very real source of recreation and creativity: bandstands, cafés, flower shows, fetes, cricket pavilions, Punch and Judy, friendly patrolling policemen, and park-keepers who locked up at dusk. These far-off days are evoked as we enter the auditorium, crossing Tim Meacock's astro turf lawn as Anthony Ingle's five-piece palm court orchestra plays discreetly.

Salad Days embodies the new post-war optimism which followed the coronation. It also takes a very sly subversive look at this watershed era: marriage, the family, social rules, upper class snobbery, higher education, fashion, the government and the police are all gently critiqued. This is expressed in the book and lyrics of Dorothy Reynolds, which have the point and convoluted wit of later Sondheim, and in Julian Slade's melodic tunes which underscore the pointedness beautifully.

As Timothy and Jane dance throughout their summer, agreeing to look after the piano for £7.00 a week - Timothy, like many highly-qualified university graduates today, forced by circumstance to take a menial job - the story negotiates their well-to-do, rather unhappy families, whose more significant life events include visits to a beauty parlour – an amusing turn from Gemma Page as Lady Raeburn, Jane's mother, who tries to talk nonstop on two phones as she is pummelled, preened and powdered – or attending an absurd disintegrating "new look" couture show which is overseen by Tony Timberlake's world-weary Augustine Williams. That there is a gay subtext to the script becomes clear by this time after we have witnessed even the staid police superintendent succumb to the charms of the piano: "Dancing is a hobby of mine," he mutters covertly to Tom Millen's young PC Lancelot Boot. But by then an entire cross section of society is singing "Oh Look at Me, I'm Dancing": even the baby dances in the pram. Quinny Sacks' choreography evokes this societal transformation brilliantly and avoids too obvious a reference to the rock and roll upheaval which was to come.

Among a talented ensemble, Kathryn Martin, as Asphynxia the droll nightclub singer, brings the house down with her rendering of the torch song "Sand In My Eyes": early Petula Clark morphing into Peggy Lee and back again via Marlene Dietrich. Mark Inscoe finds insouciant comedy as aviator Uncle Zed, who arrives on his flying saucer to help look for the, by now, lost piano. Matthew Hawksworth is an enigmatic figure as the tramp who turns out to be another uncle, 'the one we don't mention'. Ellie Robertson does a good comic turn as Jane's social climbing friend, Fiona. Luke Alexander creates a touching figure as Nigel, Jane's upper class suitor who does not realise she has already got married to Timothy, and introduces, charmingly, possibly the most catchy song in the repertoire: "It's Easy to Sing". Leo Miles and Katie Moore inhabit their roles as Timothy and Jane, singing and dancing with virtuosic abandon, and show a startling talent for physical theatre - watch for Jane's slip, slide and fall in the second act as she rushes after Timothy. The cast imitate the cut-glass fifties upper-class accents without parody, and even those without speaking roles give carefully thought-out performances.

Bill Bankes-Jones directs mostly with a sure touch, and with much pleasing incidental detail: the butterfly catcher who dances in slow motion, the cossack dancers shadowing the diplomats whose patter song "Hush-Hush" has an almost clairvoyant foretaste of the Wiki-leaks affair. There is a certain loss of momentum towards the end of the first act where the dancing segues into the angular posturings of a dance marathon. This seems more American than English, making that very English song "Out of Breath" seem almost inappropriate. Jane sings "I Sit in the Sun" while actually sitting in the shade. Lighting and special effects seem a little am-dram, and are not as slick as they should be. The second act, however, maintains pace and momentum superbly until a finale which has the audience singing along with the cast.

The late Ned Sherrin once declared that he knew of nobody who did not feel better after having seen Salad Days. I have to agree. The effervescent nature of this delightful production will almost certainly put a smile on your face.

Salad Days, at Riverside StudiosChris O'Shaughnessy reviews Salad Days at Riverside Studios.4