Thanks for all of the great photos of what is surely going to turn out to be the U.K.'s greatest ever zoo exhibit. I'm not sure how common Javan Banteng are in Europe but in North America it is almost unheard of to come across a zoo with the species. The same goes for Lowland Anoa (at perhaps only 10 zoos in North America) and it is wonderful to see those animals get such large paddocks at Chester. Islands looks to be very impressive considering the fact that the photos on Zoochat are only showing a small representation of the entire complex.
Bantengs are not really rare, but not common either, at the moment there are 17 European zoos with the species, of which 1 is going out of the species soon (Karslruhe), except two zoos all holdings are concentrated in only 4 countries (Germany, Netherlands, France & UK). Many zoos breed quite well, so I would not be surprised if they pop up in more zoos within the next few years...