Are you sure you want them Womble? Sloes grow on blackthorn, which is a vicious, spreading thug. It's way of self-propagating means it creates great impenetrable thickets which trap sheep and people trying to cut them down, and their thorn scratches take months to heal. Horrible stuff. Much better to pick the sloes from someone else's trees.
Also, from Mr Google: <<Blackthorn Toxic Components Being a member of the Prunus family, Blackthorn contains varying amounts of cyanogenic glycosides---which convert to cyanide (prussic acid) when plant parts are chewed, crushed, trampled, or grinded. Cyanide is a highly toxic poison, which is quickly absorbed from the gastrointestinal tract into the bloodstream.>>
I'm not sure that 'grinded' is a word, but you get the idea.