Just back from a great trip and thought I would give some feedback on our experiences.
Binoculars of some type are essential if you want to make the most of a safari trip and you really need a pair for each person. I was very surprised to find that we were in the minority for both taking binoculars with us. Our guide said that he has even heard of clients not even bothering to take a camera with them and just using a mobile phone!
Due to some unforseen circumstances, our shopping was very last minute and we were not able to make the most of the advice you all gave me. I hope nobody is offended.
My wife bought a pair of Nikon 8x25 roof prism binoculars from John Lewis, which were alright. I paid a visit to microglobe in London, who were mentioned in the thread. They have a really good selection on their website but the shop itself is a bit of a shambles and the staff clueless - call ahead if you are thinking of visiting. They didn't have any models at 8x32 or x 36 in stock and the x42 ones were out of our price range. I tried a couple of pairs there, and the best at a reasonable prices were Bushnell Powerview 8x25 porros, which I thought were surprisingly bright and clear and also very light (cheap too - £35).
The comments that at the cheaper price points porros are better value than roof prisms certainly seemed to be true and the pair I chose outperformed more expensive roof prism models by the same maker.
I was a bit concerned about 8x25 being too dim but this did not prove to be the case - they performed very well, even in lower light. Sure, bigger would have been nicer. Where they did fall down was in the reduced field of view - it took a while to hunt down the target, especially when searching for birds in branches.
Weight and bulk were more important than I expected - it was no trouble to keep the binoculars with us all the time and they were easy to slip in to day-sacks/ hand luggage along with cameras etc.
Roads are very very bumpy over there and everything takes a bit of a pounding. I would really recommend choosing models with some sort of armouring - my pair took a couple of big knocks while I was trying to protect my camera.
Kenya can be very wet, so it might be worth looking for waterproof models - ours weren't but we didn't have any problems.
The trip itself was excellent and we got to see lots of wildlife and meet some interesting people. I can really recommend a safari to anyone who gets the opportunity. Will try to post some photos once I have sorted through them.
Thanks again for your help
Dave