Interesting...
Now assuming that's right, and unless there is some other Justin Webb, I think we are talking about a very prominent BBC journalist who is currently the Washington bureau chief and is about to take over as presenter of Radio Four's breakfast news programme, Today.
Unlike the last journalist on the programme, John Sergeant, he has no background in comedy, as far as I know.
I will be very interested to see if this is correct.
EDIT : In the Yahoo group, it's been suggested it could be Justin Edwards.