That looks like a male village weaver (Ploceus cucullatus).
Sorry if this is wrong, as birds aren't my forte. Marwell had the attached sign located beside the aviary.
Weavers do seem to cause some confusion - and I'm not immune - especially as the male's plumage changes when they're breeding and according to region. I think one of the best guides is the colour of the eyes, although even that's not infallible.
This is a typical example of a male Ploceus melanocephalus: Black-headed Weaver - The Internet Bird Collection
...and this Ploceus cucullatus: Village Weaver - The Internet Bird Collection
Separate names with a comma.