Thanks guys. I've put up another version below, with less blue; as suggested by Jeff (thanks!) and backed up by Alan's comment - hopefully not too warmed up!
This magnificent specimen was part of quite a large herd. We were driving in Kruger, when another driver flagged us down and alerted us to the fact there were rhinos ahead. We came across then in a clearing, shortly after that, and spent a long time (about an hour) watching and taking photographs. The subject of the photograph was obviously the leader of the pack and has an amazing length of horn. I posted another picture of a different member of the pack as an earlier post on this forum which shows the more normal stubby horn.
The fight against rhino poachers was very strong in the time we were in Kruger and we were on our way bck to camp rather late one evening when wer were stopped and questioned by an armed patrol (scary!) - so much so that we arrived back at the camp after dark and when the gates were locked. Even then, after half an hour, two of the wardens who had been with the armed patrol came to visit us to check that we were indeed from the camp and the details we had given them were correct. It is clear then that South Africa are doing what they could to stop this evil trade with its devastating consequences on the survival of the Rhino population - indeed this problem was something that was constantly brought up at the three camps we stayed in during the 12 days of our visit.