as far as i know there only eaten when cooked or steeped in alcohol, they look like fat hard blue berries but darker, have a single stone (like a plum, think there part of the plum family)
the leaves are an oval shape witha center vain, ranging from light to dark green, white flowers that grow off the branch, that have the long about 2inch thorns
included a pic i took while picking them as its my 1st time and i had to be sure, sent pic of to a friend of mine that does all this hedgrow foods thing
They look like plums, never thought about what a sloe gin fizz consisted of. We don't have those here I dont think. Looks like a website for flora/fauna for UK would have it listed.
I don't know about sloe berries but I know Puffin would do just about anything for a blackberry or kankleberry! The downside is the mess he makes with them!