Hippies in a slate quarry in Wales are celebrating four decades of green revolution this weekend, having transformed the character of a local town, pioneered new energy technologies and constructed a water-powered railway.
The Centre for Alternative Technology (Cat) near Machynlleth also created hundreds of jobs and a tourist attraction that draws in around 70,000 visitors a year.
Many of the radical ideas from the centre in mid-Wales are now thoroughly mainstream. Alternative technologies are no longer alternative, as the world seeks to tackle climate change and diversify energy supplies.
But the centre’s original aim to democratise technology remains unfulfilled, and there is a realisation that its mission is far from complete. Its radical recipes for achieving a zero-carbon Britain remain unpalatable to politicians and the public.