After a lot of sleuthing, and misidentifying, we might have two elderly plum trees in the garden!

D has tried them and although tart and not very squidgy, we are close to calling them plums. Diddy little plums but we have ingredients for crumble or jam! The thorns led us to misleading identification as blackthorn but even Google lens was happy to say Victoria Plums!
My local ish pals with garden knowledge also said plums and I was encouraged to try them. Luckily there doesn’t seem to be a poisonous equivalent and even if they are small, the options for stewing them seem multiple and then that leads to Jam or crumble. Yay!

We did plant our own plum tree when I had a significant birthday during lockdown so perhaps we introduced a cross-pollinator inadvertently and our serious prune earlier this year, encouraged the growth of lots of fruit. Bring it on! Hopefully we can harvest before they feed the wildlife running between the back gardens. (Foxes, cats and miscellaneous animals have been seen by our rescue dog at ungodly hours of the night!)
