A situation has arisen. This is quite obviously Sarcogyps calvus; even with my poor ID skills I was quite confident as to the ID but was busy and wanted a confirmation. Now that I have got two I am quite satisfied with the ID.
However, a quick search of the 2010 inventory for Mysore Zoo (when and where this was taken) shows no mention of the species, only Aegypius monarchus, cinereous or black vulture. It could be, and is quite likely a misidentification, considering that similar inventories claimed that certain zoos held Sumatran Eagle Owl when the original was clearly an Indian Rock Eagle Owl. This in turn further complicates matters for my other raptor ID taken at the same zoo, as despite the zoo listing Tawny Eagle it could be something else.