From the moment the curtain rises on Avenue Q, with a short and cute introductory cartoon, giving way to a street set filling with muppet-like puppet characters and humans, to the strains of the Avenue Q theme, you are in no doubt where the inspiration for this show is drawn, and you are in familiar feel-good territory. However, as our ‘hero’ Princeton arrives in this down at heel suburb of New York, fresh from college, wondering “What do you do with a B.A. in English?”, and encounters his new neighbours, who each believes “It Sucks to Be Me”, you realise that this is not quite the safe and saccharine world of Sesame Street. It is more ‘Sesame Street meets Sondheim, where every character, puppet and human alike, have their flaws and their failings.

Where the legendary US kids show educates the audience in their ABCs and times tables, this very adult pastiche handles the more knotty problems of the human condition, including racism, sexuality and crushed ambition.

Among the cute and fluffy puppets, we have Katey Monster, a teaching assistant who dreams of love, and of running her own school; Rod, a closeted gay banker who secretly yearns for his straight flat mate, and Trekkie Monster, a hermit-like grouch, who delights in singing the less academic benefits of the worldwide web, in “The Internet is for Porn”. The humans are Brian and Christmas Eve (Edward Judge and Jacqueline Tate) - an out of work loafer, and his Japanese therapist girlfriend, and Gary Coleman (Matthew J Henry) - former child star from TVs Diff’rent Strokes, now reduced to janitor on the block.

With clever songs, by Robert Lopez and Jeff Marx, who also devised the show, that have a cheery feel-good bounce, but often angst-ridden lyrics – “If You Were Gay”, “Everyone’s A Little bit Racist”, “There’s a Fine, Fine, Line”, “Schadenfreude” and “For Now” for example – and a real laugh-out-loud script (book by Jeff Whitty) Avenue Q is a rare joy. Although covering some tough issues, the show never delves too deeply, preferring to make us laugh at our own preconceptions and reactions.

Avenue Q’s unique selling point is that the puppets are operated and accompanied on stage by actor/puppeteers who not only animate and voice the parts, but act their hearts out. Through the magic of theatre, they transpose all emotion onto the puppet, whilst remaining visible to the audience at all times. It sounds crazy, but somehow it works - you utterly believe in the characters, whilst appreciating the human performances behind them. Adam Pettigrew, who animates Princeton, is superb, and Rachel Jerram delights in her dual role as the sweet and homely Katey Monster, and sassy siren, Lucy the Slut. Ably assisted by Katharine Moraz, and Chris Thatcher, for who top marks must go, in his wildly contrasting roles of Nicky, Trekkie Monster and one of the ‘bad decision bears’, showing a staggering vocal range and great comic timing.

Directed by Jason Moore and brought to regional audiences by The Theatre Royal Bath and Cameron Mackintosh, Avenue Q is only slightly let down by an overly schmaltzy happy ending. A sometimes shocking, riotous and surprisingly tuneful evening is guaranteed.