Bindweed

Calystegia sepium - probably! I think this is Hedge Bindweed, but I need the flowers to be sure.

Anyway, in the garden it is enemy number one and I am not ever so keen on seeing it out here... It is beginning to scramble up and over other hedge plants. Still, I expect in the 'wild' it will achieve some sort of balance. It twines anti-clockwise - unlike honeysuckle which twists clockwise.