Senecio fuchsii (S. nemorensis seems to be more or less the same).
One of those plants that should have been a British native, but isn't, and although it does a fantastic job of brightening up the dark and dreary hedge bottom at a time of year when not much else does, is not the sort of thing which leaps out at you as the perfect new border plant.
A plant which raises questions then.
First of all, why is it all over woodland edge habitats in hilly areas from Belgium down to Bulgaria (from whence comes my stock) but not Britain? And why doens' it look quite garden worthy.
Its absence from the British flora can only be put down to everything having been scraped off by the last Ice Age and it not having a chance to blow back in, when the English Channel effectively pulled up the gangplank on the full flora of northern Europe re-establishing itself.
And its looks? Too much like ragwort for some (related of course, but completely different in its details of leaf and flower shape, and not toxic). The leaves are a lovely dark green, the flowers plentiful and a good yellow, but there are petals 'missing' so there is a kind of scruffy feel. And a re-design would definitely make it a bit shorter than its current 1.2m, and therefore less likely to flop.
One for some selection and improvement?