After a few very successful years, my wisteria is having a horrid spring.

It has a few leaves dotted all over, so I know it's alive, but instead of
flowers it has a smattering of dry, husky catkin-like "flowers" - no bigger
than acorns, all over. I didn't prune it at all in the last 12 months (shame
on me).

I thought they were meant to be pretty hardy - it's on a SE facing wall in
Shropshire. Might this be the result of a late March/Early April hard frost,
or is there something more sinster going on??