I don't know what this tree is. I think it might be euonymus hamiltonianus (spindle tree). It's in the Celastraceae family. It's got lovely four-lobed berries on it at the moment and the foliage is starting to turn maroon at the edges of the tips. Apparently the pink-red berries should open out to expose bright orange seeds and is great for birds.

Leaf and berry of euonymus hamiltonianus