So sorry it's blurred - and it's 3ft 6ins.

I think it's salvia uliginosa

Well, that’s brilliant of you Andrew, thanks! New to me but I will try to propagate it.

yes I think Andrew has it spot on. common name is bog sage and is native to Sth America. should come true from seed.

Thanks Eileen - I’ll definitely try to collect the seed 🙂.

It will clump up so you should be able to divide it (in spring) in three to four years' time

Thanks Andrew, that sounds good. And I’ve just taken a couple of cuttings 🙂. Appreciate your help both of you.