Seen growing in a street, and presumably a garden escape.

http://www.stewart.hinsley.me.uk/Images/IMG_3000.JPG

Not Saxifraga (cordate rather cuneate leaves), nor either of the
pennywort genera (leaves not peltate), nor Pyrola (leaf venation palmate
rather than pinnate). It doesn't seem a bad match for Homogyne alpina,
but that's restricted in the wild to Caenlochan NNR in Angus (if still
present; the BSBI don't have it as being recorded this century), with a
presumably casual record in Northamptonshire, and it's rarely if all
cultivated (last seen in Plant Finder in 1997).

Anyone recognise it.
--
Stewart Robert Hinsley