Update - April 2006
Pauline Sykes tells me of another work published by Unicorn Books: a string-bound volume called The Tribal Dharma - An Essay on the Work of Gary Snyder, by Kenneth White, printed and published in 1975 by Unicorn Bookshop, Llanfynydd, Carmarthen, Dyfed SA32 7TT (ISBN 0-85659-023-1).
 

Update - March 2009
In e-mails to me on 25, 26, and 27 March 2009, Tony Bennett of London, UK, wrote:

I just came across your website of Images of Wales when I was looking up Nant Gwilw on the internet. I lived at Nant Gwilw from 1972 to 1975 when I was part of the Unicorn Books publishing co-operative and spent some of the happiest years of my life there. We had a printing press in the barn (not driven by the old belt drive I'm afraid) and kept cows, pigs, chickens and goats and grew all our own food. Unicorn published some 150 books overall.
My daughter was born there in 1975 and Unicorn closed the same year and we all dispersed for other parts. She has never been back and after many years of my promising to show it to her we have decided to make a visit this spring. I was shocked to see its derelict condition in your photographs.
Checking with the Land Registry I have discovered that the farm buildings and yard and land adjoining to the north and east were sold in January 2009 to a property company in Oxfordshire. So it is possible that someone is at this moment working on restoring the property.
I have attached (below) the only old photo of the house that I still have. This must have been our first spring as the vegetable garden to the left appears to have only just been prepared and we are still using the cement mixer. We had run a phone line, going left, up to the barn containing the printing press. On the end wall of the house are four pear trees, from whose fruit we made a passable Calvados type drink in our home-made still. In the middle left of the image, above the vegetable plot, was a small pond, fed by the Nant Gwilw stream, from which we got our water for the first few months. I cannot at this time remember what the other brick building was. I don't think it is the old dairy/cow shed buildings that are by the road, as it appears to be too small and a lot newer.

Above: Tony Bennett's photo of Nant Gwilw c. 1972, and (below) my own photo of 2003.
At least one of Tony's pear trees seems to have survived 30 years of neglect!

And in a lengthy interview on the Forbidden Planet 'Blog Log' in September 2006, Tony Bennett recalled:

I was working with a publisher and distributor called Unicorn Bookshop, originally in Brighton. We moved to a farm [Nant Gwilw] in West Wales where we were growing our own food and had a printing press in the barn. Unicorn, as well as publishing books on self-sufficiency, cannabis and poetry, was importing Underground comics from the USA. This really sparked my interest in comics, partly for the wide and weird content and partly because they were creator owned. It even encouraged me and a friend to draw and print our own self-indulgent heavily derivative comic, Trip Strip, which we distributed at Festivals.

Many thanks to Tony Bennett for providing this first-hand evidence of Nant Gwilw's links with Unicorn Books.