Cornus canadensis, the creeping dogwood.

Sorry Jimmy. but I think this is Houttuynia cordata

I agree Houttuunia cordata, I just looked it up. Fascinating plant - it's a relative of black pepper (piperales) and more distantly of Magnolia (Magnoliids). Also edible, with the leaves being used in Miso.

Houttuynia cordata Chameleon - there is a plain green version of this plant, but yours does appear to be Chameleon which, although it emerges green initially, colours up quite quickly - unless its in shade. In partial shade, the colours appear, so the fact yours doesn't colour up till after the flowers might mean it doesn't get enough sun till this point in the year, when the sun is already a little lower in the sky.

I've been trying to rid part of my border of it for three years and can't. I'm going to have to resort to weed killer - and as for the smell - sickening!

Boy, I agree about the smell, Cammomile - one garden centre selling it on line described it as 'scented' with 'hints of cinnamon, citrus and pepper'.I'd be more inclined to describe it as rank, bitter and distinctly malodorous myself.

Quite right OB. I should have given it a bit more thought. It was the green leaves and white flowers, I didn't consider the coloured ones. Planted it in my previous garden, very invasive and took me ages to get rid of. Strangely enough, particularly well in boggy soil!

We think it smells of orange peel when wet. We grow it in our pond and in the garden border.

Thank you all for informative answers and the mystery solved..
My plant sits in partial shade , so I'll start to divide it over time and move it around the garden for best light and colour.

It's interesting how different people react to the scent. I think it's like tangerine, Mum thinks it's pineapple and others, like Cammomile and Bamboo, loathe it!

I've got this vague theory that people who think this plant smells okay or nice also think that Choisya foliage, when bruised or cut, doesn't stink horribly (which it does) but find it pleasant.

A colleague of mine once told me that her husband said her favourite perfume smelled exactly like fly spray!