I look like Michaelmas Daisies to me. (Aster)

Thanks Alextb, they're not in my garden, but I see tinier versions of them all over the place down here, I wasn't sure what they were.

Erigeron karvinskianus?

yep...those bloody Erigeron. Spread everywhere

Love Erigeron but they don't self-seed in my garden - wish they would.

Otherwise known as Mexican Fleabane. I love them :)

I love them too, they seem to be on every country lane down here growing out of the stone walls. And yes they are definitely erigeron, I googled it and they look exactly like the picture. Lovely to know these things, thank you everyone. (I think mexican fleabane will be easier for me to remember !)