Why is the PM salary seen as such a benchmark? What they are actually paid is the absolute tip of their earning potential, especially once they leave office. If they are so minded, at that point directorships, public speaking, memoirs, etc. etc. give them a massive earning potential on the basis of the job. I don't know the figures off hand, but one thing that the recent spotlight on expenses has shown is that many MPs have income additional to their salary through consultancy or director roles in the private sector - additional income that they can access because of their role
I am not arguing for or trying to defend the salaries paid to some CEs, although in some cases these are people running multi million pound businesses and the wages need to be fair as the right candidates need to be in place, and HAs are operating in a market place after all - personally you could not pay me enough to take on that role. However I am more questioning the smokescreen or misleading comparison that is the salary of the PM.