I'd suggest Vinca - but it might take over - so buyer beware! lol. It does have attractive flowers, though, and there are variegated ones which you might like. Don't go for Vinca difformis though - it's a real thug!

Quite a few of the hardy geraniums are virtually evergreen ; the macrorrhizum group spread easily and are pretty tough and dont mind poorish areas such as under or between hedges.

Many thanks for suggestions will give it a go.

Graham