Yellow cave

I was feeling slightly depressed at today's weather - by the time I got out it was decidedly grey and there was a nagging wind that stopped all thoughts of summer. And then I saw this tree - I think it must have been half-blown over by a gale - dripping its golden flowers over the path in the overgrown grounds of Toward Castle. It was like a cave of sunshine, and it restored my delight in my surroundings in an instant.

Incidentally - what is that tree?