In article , kenty ;-)
writes
Can anyone give any advise on when & how to crop damson.This is my first
year in my house so I haven't cropped before.The fruits at the moment are
starting to turn purple.

Pick them asap or they will soon be attacked by wasps. If they are not
quite fully ripe, they will become so after a few days indoors.
--
Alan & Joan Gould - North Lincs.