Deep down, this musical version of the film that made Tom Hanks big, wants to be small. It first opened on Broadway in 1996, has stirring, chorus-line numbers, a set with huge electronic displays that conjures suburban America and a large orchestra that fills this cavernous auditorium with a solid — though hardly inspired — score by David Shire (music) and Richard Maltby (lyrics).

Yet, for all that, Morgan Young’s bright, brash revival of this 1996 Broadway show, is most effective when it is at its most intimate — or, you might say, small.

When we first encounter him, Josh Baskin is 12 years old, too shy to talk to a girl and too short to take her on a hair-raising fairground ride with a height restriction. For those still too little to remember the film, Josh’s wish to become big is granted by an old-school carnival machine. He wakes up the following morning with the body of grown man, played here by Jay McGuiness, formerly the frontman for boy band The Wanted. My guest took one look at the poster and couldn’t believe the show’s star — also a winner of Strictly Come Dancing — is in a boy band. Was, I corrected.

Still, McGuinness retains enough boyish charm to cut it as an adolescent trapped inside a grown-up’s body, though you do miss the guileless innocence that Hanks brought to the role. More problematically, the moment of transition from small to big has few of the laughs generated by the movie, although the transition back from big to small at the end of show has a magic about it worthy of Harry Potter.

For the most part, the show plods along until 12-year-old Josh and his new 20-something body is given the dream job of toy tester by Matthew Kelly’s toy tycoon. We are a good way into the evening by then, however, and only when powerful but lovelorn company exec Susan (a likeable Kimberley Walsh) falls for the man with the child in his eyes (and his brain, too) does the show get close to the laughs of the movie. Unbeknownst to Susan, when Josh declares his preference to being on top, he’s talking bunk beds, not sex. But where the show really scores is in the scene where it ditches all the big musical paraphilia and Josh has to negotiate the vagaries of grown-up dinner party etiquette with Susan’s sophisticated, urbane friends.

Here Shire and Maltby’s score beautifully conveys the distance in taste and sophistication between adults and children with a cod-operatic number — by far the wittiest moment both of storytelling and music writing. And granted, the number in which a child’s optimism forces a chorus of grey-suited execs to drop their cynicism gets close to the kind of ecstasy that only musicals at full throttle can achieve. But it doesn’t quite get there, and anyway the scenes that will stay with you are much more intimate and are all about something much more subtle than this production wants to be. It teaches that few adults retain the honesty and openness that goes with being small.