My default is to compare other public sector salaries to the basic armed forces pay scales. I reproduce these below.
Now, do you think that GPs should earn the same as Major Generals? Or, perhaps like me, you think they should be paid at about a Major's wedge? Should a primary school head earn as much as a Lieutenant General commanding a division, or should the head's pay be more in the Lieutenant Colonel range? For what it's worth, I also reckon council chief executives are worth no more than Major Generals and an NHS consultant at the top of his game no more than a Brigadier.
The spread, from the base salary to the highest, is about 7.5x. This is actually about right, and within an NHS hospital trust or a local authority this equates to a spread of about 6x between the base admin officer salary and the chief executive's - in fact, the spread that used to apply before the insanity of fat cat salaries at the top drew open the gap to something like 12x.
We've got to get the differentials right. If I were an Admiral commanding a flotilla of some of the world's deadliest warships, and responsible for the lives of the crews, the safety of the public and the defence of the realm I'd be a bit miffed to learn I earned the same basic salary as a Sri Lankan locum GP in Dulwich scratching his balls and enjoying a five day week with no call outs.