Outside the tent is a sign that reads ‘Last ever Welfare State gig' and this is indeed it: Longline Carnival Opera is WSI's last bash and the culmination of three years' work about, with, and for the people of Morecambe Bay; an everything-including-the-kitchen-sink extravaganza that brings together contemporary music theatre, agit-prop circus, moving image, puppetry and storytelling (to name but a few of the component parts) into one great soup of a show. It's a rich and full experience. The music (under the direction of Tim Fleming) is wonderful: having been to the show twice, I was particularly appreciative on the second hearing. The made objects are lovely: they include a 'model village' Morecambe Bay, a junk-sculpture elk puppet, Bunraku-style wooden puppets representing four archetypal characters, and a rag-bag metal-machine.

A trio of clown-guides (in their guises of Heron, Moon and Raven) carry us through the story, which circles around the fate of The Rock (the ancient Morecambe Bay landmark that was the focus of an installation-exhibition work in the first phase of Longline). Ultimately, the piece takes a Gaian viewpoint: if we humans are stupid enough to pollute, terrorise or otherwise trammel ourselves out of existence then that's our loss – the earth, as epitomised in The Rock, will live on, as it has for millennia.

An extraordinarily large cast is involved in the making and performing, reflecting the company's ethos of removing the distinction between professional and amateur performance. It's a rather loose-limbed piece; perhaps a bit too long and certainly with some awkward moments where things don't quite slot together properly. I also feel that some of the young performers (including the narrator) seemed a wee bit lost at times. But what does it matter? All's well that ends well – it all came out in the wash; and Longline was a fitting end for Welfare State. An unashamedly populist, entertaining, life-affirming, celebratory theatre show.