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from "Sue" contains these words:

I wondered about bullace but isn't a bullace more of a greeny colour?
(outside I mean). I am just about to jam them now anyway.

IIRC this came up this time last year and surprised me.

If you look at Bullace in Google Images they show both colours ...

HTH ... Jennifer

Someone last year posted a link to a site with dozens of varieties of
bullace and damsons and the various species involved, needless to say I
can not now remember what I did with it!

--
Charlie Pridham, Gardening in Cornwall
www.roselandhouse.co.uk
Holders of national collections of Clematis viticella cultivars and
Lapageria rosea