Like surprisingly lots of musicals, the subject matter of The Pajama Game - they say pajamas, we write pyjamas - is distinctly unpromising. But this tale of love across the picket line as the workers threaten industrial action over a pay rise is a Broadway classic, and Richard Eyre's Chichester Festival Theatre production makes a joyous leap from the Minerva studio (where it opened last summer) to the vast open spaces of the unforgiving Shaftesbury.

It's lit from within, this show, with a handful of songs that should by rights be dated but which still make you glad to be alive and never cease to spring endless surprises in their melodic invention and rhythmic variety: we all remember "Steam Heat," "Hey There (You with the Stars in your Eyes)" and "Hernando's Hideaway" but the Sleep-Tite pajama workforce also really sock it to us while "Racing with the Clock" and taking time out on a company picnic on their "Once-a-Year Day."

The last London revival, directed by Simon Callow 15 years ago, turned into something of a "nightie-mare," over-produced and oddly and abstractly designed by the American painter Frank Stella. Eyre and his team - choreographer Stephen Mear, designer Tim Hatley and musical supervisor Gareth Valentine - make no such mistake, releasing the freshness and energy of the show with untrammelled simplicity and affection.

And in the casting of Michael Xavier as the factory superintendent, Sid Sorokin, and Joanna Riding as the bolshie union rep, Babe Williams, they have two delightful stars who inhabit their roles and jim-jams with perfect precision and in perfect harmony. Songwriters Richard Adler and Jerry Ross only wrote two hit musicals - Damn Yankees is the other one - but they never left room for improvement.

The witty, fast-moving libretto was the work of George Abbott, one of Broadway's legendary professional fixers, and his colleagues on the 1954 premiere were Hal Prince and Jerome Robbins, achieving lift-off from a novel by Richard Bissell which gave them a good lead on the cheerful, chaotic atmosphere of an Ohio garment factory; it's the transformation of that setting into a completely realised musical theatre environment that is the key to success, and this production gets that exactly.

The musical numbers are seamlessly incorporated. There's an overall grace and fluency about Eyre's production that can only come from treating the material with utter respect, and that's not a deadly virtue; or, at least, it's not here.

With a superbly drilled chorus and wonderful support work from Peter Polycarpou as Vernon Hines, the time and motion man (he will be succeeded by Gary Wilmot next month), Clare Machin as Mabel the secretary and Colin Stinton as the apoplectic boss, the whole confection bubbles like a fresh water stream so that you have to pinch yourself to remember Jean-Luc Godard's unappetising recommendation of the show as "the first left-wing operetta." The hell it is, but politics can be fun, too, it seems.