The picture represents the Goyt valley with its reservoir and the celebration is in praise of water. It's all made of seeds, petals, flowers, stones, wood, leaves and it was like making miniature pictures in the garden when you're a child (only this was serious stuff ! ;-)
There's an interesting gender divide whereby the women make the picture, the men carry it out and assemble it. Bits drop off and the women blame the men. It's a tradition!
Anyway, I went along again today for the little ceremony where school children sang beautifully, the local band played and the vicar tried to lay church claim to this pagan custom.
I thought the final result looked great. I've been invited to help make it next year. That must mean I'm local now!