It tumbles over the walls of the gardens of - usually old - houses like the picture.
The flowers are white and the leaves are silver - grey - green. I've googled like mad but it always comes up with aubretia and creeping phlox, which have normal green leaves. They'd do the job but I've got my heart set on the other one.
Does anyone know what I'm talking about?
(Picture won't load and I can't work out why. I hope you get the gist.)