It was a 4 foot shrub growing between some gorse bushes. Had just a very
few stems, covered in quite big spherical pale yellow flowers (but not
very
substantial looking, like e.g. mimosa).

Was driving down the Oxford ring road at the time, so details might be
dodgy


Any ideas?


Thanks all, but it's not anything that anyone suggested.

I'll have another look out for it this weekend and maybe get a picture.