Thanks to all for the answers: seems like the hard winter has been the
problem. (We're in the North East of England here.) We didn't get much
blossom (didn't expect much, as it's still a young tree) but we had
expected a _few_ plums.

I know now that I need to prune it quick while it's still summer, but
only to the extent of shaping it.

And thanks to the great videos at
http://www.articlesbase.com/videos/5min/166434895 (thanks Steve The
FruitGrower) I know how to prune it.

---

By the way: there's a plum tree next door-but-one to us - grows out of a
crack in the ground between the house and the street; it's probably 15
years old now, and has had nothing whatever but _neglect_: it grows
ever heavier crops, year after year after year: tons of beautiful plums.
All the neighbours help themselves, the owners never being around, or
caring, to harvest them. My wife was hoping to emulate this specimen
with our own.

Also by the way: Yes, I know that Google is my Friend, but it's
newsgroups like this where one can get directly to the best advice, and
usually from people speaking from experience.

Cheers all
John