Speaking as a modern Brit, it seems that Edwardian English is fast becoming indecipherable. I certainly needed to shift gear to get all the words. I wonder how many generations it will take before people are unable to recognise what he's saying?
I think some of the phrasing is mimicking Old English pronunciation. Combined with his natural 'posh' accent and the poor quality of the recording it does make it a little hard to make some of it out.
Yeah; I didn't have trouble with it particularly, but two things I noted:
1) He has a very strong trill to his rhotic "r", which I think must be put on for effect.
2) Does he have a slightly South African accent? I think he left South Africa at a young age (three, maybe?) so it seems odd that he still would at 60, but I'm not sure.
Yes, I wasn't sure about the rolled r. I could certainly make it out once I had shifted gear, but I have extremely received pronunciation myself; I wonder what someone with a more modern ear would make of it.
While it's more difficult to understand, I, as a non-native speaker can understand him pretty well. I think it's just lack of being used to a certain dialect (present or past).