Paul - I think it depends on what team he has behind him as to what is sensible to pay, by that I mean there is no point in paying someone £50,000 per year if he has 3 assistants. If he has a crew of 12 then its probably in the ballpark.
Top greenkeeper's can't do much with low budgets, equally it is easy to waste money with high budgets. What is really needed is a general manifesto of what is required and from there the cloth can be cut.
If your looking for numbers as a rough i'd say;
£18,000 for a head man with one assistant
£20,000 for a head man with two more in the crew
£23,000 for a head man with three more in the crew
£26,000 for a head man with four more in the crew
£29,000 for a head man with five more in the crew
the top greenkeepers will be looking for courses with a decent crew
£35,000 for a team of 7 up to £45,000 for a crew of 12
after that the very top guys are getting paid close to £100,000