This is growing in the greenhouse and may be a weed but I hope not as it is very pretty and I would like to add it to pots and use as ground cover under shrubs etc.
It looks like a Persicaria bistorta, but there are lots and I don't know which one this is
Sorry I appeared to have chopped some of my answer. Should have read ... You are right, I have looked it up and it is Persicaria Capitata (as Edd says) and I shall be planting it in the greenhouse as that is needed for tommies! Thank you both.
I spent a lot of my childhood hoeing sugar beet fields by hand and there's a wild persicaria that loves those conditions - it's ingrained in my memory - there was a pull-out of arable weeds from the Farmers Weekly on the wall in the boot room!
Perhaps it is a wild plant but it is rather lovely and I have already transplanted some of it in a little rockery.
Thank you everyone.