The book is called "Wild & Free 100 Recipes & Folklore of Natures Harvest" by Cyril & Kit O'Ceirin 1978 The O'Brian Press
There are a few interesting things about the folklore of the Blackthorn
A sloe year is a low year
A haw year is a braw year
200 years ago it was used to forge Port Wine, it was used as a purge by doctors, dyes linen pale blue. The much maligned Irish cudgel was often cut from the wood, An astringent Tea ("Irish Tea") was made from the leaves which were also made into tobacco
This is the bit I was talking about
"When we were children, it was quite common for people, especially the younger ones, to cram a jar with sugar & sloes (previously pricked with a pin), cover with lukewarm water, cap or cork securely and bury it until Christmas. This was called Sloe gin and was probably mildly alcoholic because of the action of the wild yeast" What we call Sloe Gin these days is actually Sloe Liqueur
Great Book if you can get hold of a copy