Who are you (or I for that matter) to tell Sir William that his recommendation is scientific nonsense. He has been a scientist for over 4 decades, including being responsible for leading the team that developed the Anthrax vaccine, and has been the chief scientific advisor for two British governments. He has looked at the literature and said there is concern from the research around phone masts. It makes no difference if the exposure is 10 times high from phones if something is found specifically at the exposure levels from phone masts. And if that is the case, moving them closer would be stupid.
It is possible he is simply going senile, but I rather doubt he would still be chairman of the HPA if so.
Don't take this the wrong way, but I trust his expertise more than either of ours. I suspect you just are completely unaware about the amount of scientific literature out there on health effects from exposure to base stations - If so, why choose to make a judgment about a subject you don't understand well enough?