Hardy down to -5 deg C, but should be planted in a sheltered, sunny position in rich, dampish soil. If the tree is young, can be cut to the ground in spring if growth severely damaged by frost and it will regrow.

If it needs pruning, only do it right after bloom, since the buds for next year's flowers form the previous late summer or fall. High winds in winter can also damage the buds, so you might want to plant it in the lee of a tall evergreen, or very twiggy deciduous tree, such as an ash or elm.

Elm Tugbrethil? You are having a laugh, I assume - there's not an elm tree in the whole of England by now, apart from seedlings which then succumb to the disease too...

Rats! I didn't know that it had got you guys, too!

Ages ago I'm afraid, think it was the late eighties/early nineties.