I expected to see the bull Hugo in the old pen, but I think it may be either Behan or Beluki. Unfortunately the other two rhinos in the newer pens were in the pool and down by the railway line respectively, so I couldn't recognise either of them.
@gentle lemur Its either Beluki or Behan. Hugo has a straight back- rule of thumb in most rhinos- dipped back = female, level back = male. Since the female with the longer horn lost it I can't identify the two females so easily anymore. I think at present its just the three adults at Whipsnade.