It’s time to play the music, it’s time to light the lights, it’s time to raise the curtain on The Muppet Movie’s 40th Anniversary tonight!

If you were born between the 1970s and 1990s, it’s almost impossible to imagine a world without “The Muppets”. From “Sesame Street” to “The Muppet Show”, they formed one of the cornerstones of childhood pop culture and while they have endured, they’ve yet to recapture the dizzying heights of their late 1970s/ 1980s dominance. That’s thanks in large part to the irresistible amiability and boundless charm of this, their first full-length movie, released in the UK 40 years ago today.

Riding high on the TV success of “The Muppet Show”, by then in the middle of its third season, “The Muppet Movie” takes a typically metatextual approach to telling the origin story of the Muppets themselves, weaving a wondrously bright and breezy musical comedy road trip as Kermit sets out in search of fame and fortune and finds fun and friendship along the way.

Awash with big-name cameos from Hollywood’s great and the good, the film still belongs to The Muppets themselves and each of your favourite characters gets time to shine with most of them getting some great musical numbers along the way too. The film opens with the iconic ‘Rainbow Connection’ – nominated for Best Song at the 52nd Academy Awards (where it undeservedly lost out to ‘It Goes Like It Goes’ from “Norma Rae”) – but after that the hits keep on coming and there’s even a nod to “Sesame Street” as the gang, heading west, pass Big Bird heading east to ‘break into Public Television’. Big Bird would, of course, get his very own movie some six years after his big-screen debut here.

Freed from the constraints of a television studio and budget, Henson and his puppeteers, together with director James Frawley, really upped their game, famously showing many characters’ feet for the very first time and wowing audiences with clever sight gags and cleverer puppetry tricks, such as Kermit riding a bicycle. Throughout its leisurely running time, “The Muppet Movie” showcases that unique magic that Jim Henson’s creations had – a combination of wonderful vocal performances, deceptively simple character design and peerless puppetry skills, creating fully realised characters you never once consciously think of as anything but alive.

It may seem quaint and old-fashioned by today’s cynical standards but it was ahead of its time when it came to ironic self-awareness, revelling in the fourth-wall breaking potential of its movie-within-a-movie conceit and even doing the film burning through gag which fellow puppet extravaganza “Gremlins 2” would homage a decade later. Relentlessly likeable and wholesomely sweet, but with a knowing wit that keeps it from ever getting too saccharine, “The Muppet Show” is a timeless piece of family entertainment and forty years on has lost none of its power to delight.