There should be a statutory ban on anyone's being paid more than the Prime Minister. As there should be on paying any employee more than ten times what you pay any of your other employees, with the whole public sector functioning as a single entity for this purpose, and with its median wage fixed at the median wage in the private sector. Possibly, that median would do as the salary for MPs. Certainly, it would not go down as a result of this measure if, as urgently needs to be happened, the contracting out of public services were discontinued and all such work were brought back in house.
Leading us to the definition of the public sector. At the very least, it includes the many politically well-connected companies dependent on public contracts. It includes the companies owned or controlled by Academy sponsors and handed lucrative contracts, met entirely out of the public purse, by Academies with, since they purport to be private schools, no obligation to put out to tender. And it includes the bailed-out banks. At the very least.