Pay for some "superheads" has topped pound;150,000, and next week state schools may well be given the flexibility to pay still more.
The School Teachers' Review Body will report on leaders' pay to ministers on Monday. It will not recommend an increased salary gap between class teachers and their heads, but it is expected to suggest new pay structures for heads who run more than one school or a federation.
The proposal has been applauded by Sir Dexter Hutt, executive head of Ninestiles School in Birmingham and of Central Technology College in Gloucester.
Sir Dexter, credited with turning round a succession of schools, said he earnt pound;131,000. But because he is no longer statutory head of either of the schools he oversees, he is paid as a private consultant. This means he has lost much of his teachers' pension, conditions of service and other entitlements.
Sir Dexter's consultancy has a pound;625,000, two-year contract with Gloucestershire council to improve standards at Central Technology College, which has its own head, Helen Anthony.
Sir Dexter described his role as equivalent to a naval admiral. "No one would question the authority of each captain over his own ship," he said. "But equally, neither would anyone question the authority of the admiral over the whole fleet."
Professor John Howson, from Education Data Surveys, said secondary leaders' pay had skyrocketed in recent years because of recruitment difficulties and was now impossible to rein in. Government figures show one inner-London head was paid just under pound;150,000; another outside London was paid more than pound;150,000 last year.
By comparison, Ed Balls earns pound;137,569 as Children, Schools and Families Secretary.
This week, Northumberland Park Community Secondary School in north London is offering up to pound;135,000 to recruit a head. Harris Boys' and Girls' academies in East Dulwich, London, are offering up to pound;120,000, plus a performance bonus.
The official figures showed at least 134 mainstream state school heads being paid above the top of the leadership pay scale - now pound;98,022 outside London and pound;104,628 in inner-London. Professor Howson said it had become almost standard practice to offer more than pound;100,000 to the principals of England's 83 academies.
But John Dunford, general secretary of the Association of School and College Leaders, said such salaries were justified. He said: "You've got to look at comparative roles in commerce and industry to recognise the significance of the role school leaders play in society - a role far beyond that of a bank manager or company chief executive."
Leadership, page 24.