Cherry or mirabelle plums. Term is pretty well much interchangeable. I have some in my garden, plus there's several along the edges of the community orchard.
That's probably the last of them, as they're usually one of the first plum species to ripen.
I wouldn't say they're my favourites. The jam they make can be quite insipid, as they lack the acidity of something like a Victoria or Czar.