Hi Lona, I'm struggling with my doorstop RHS A to Z here, it's circa 1996 so may not have more modern varieties.
I was thinking Prunus Royal Burgundy cherry before, but don't really know. You can get large oval-ish cherries, but plum size fruit will probably mean - it's a plum!
dj is right , there's definitely purpurea there colourwise, are there any spines (?)(thinking ornamental sloe) & there is a Prunus spinosa Purpurea variety.
What you need is an "I've got one of those!" rather than me waffling, nevermind - back to my doorstop....
