little blue heron

I'm not a per se a bird watcher but from time to time I notice different birds. Last Friday in the centre of Buntingford, wading in the River Rib, I saw what I believe to be a little blue heron. I'd never seen one before let alone heard of one. I understand they are native to North America and I haven't seen any references to sitings in the U K. Has anyone seen one in the U K themselves?