But taking on responsibilities makes people more interested in becoming a headteacher.One in five classroom teachers aspires to be a headteacher, according to a new survey. The figure of 22 per cent is less than the 26 per cent of graduate employees who aim to be at the top of their profession.
However, the survey of 1,002 teachers and school leaders does show that once teachers take on leadership responsibilities, they are more likely to consider headship.
Nearly one in three senior leaders hoped to progress to headship within three years - enough to make a dent in the looming leadership shortage.
"You're naturally going to see a greater ambition to leadership as people get a taste of what it's like," said Chris Kirk, succession planning director of the National College of School Leaders, which commissioned this year's inaugural Headship Index.
Ian Taylor, 26, a maths teacher at Unity City Academy in Middlesbrough, said his first passion had been the classroom. But then he witnessed a new headteacher come into his school and make dramatic improvements, almost overnight.
"I realised the power of that position," he said. "As a classroom teacher I can make a difference for the 150 children I teach. As a head, I can change the lives of 1,000."
The number of heads retiring will peak between now and 2010, creating a nationwide shortfall. The shortage seems to be lessening in secondaries but remains severe in primaries, Catholic schools and expensive urban areas such as London.
Up to 300 primary and 30 secondary schools started this term without permanent headteachers, according to the Education Data Surveys' annual leadership study.
The NCSL survey shows leadership aspirations at Catholic schools lag well behind others, but results for the primary sector and London give greater cause for hope.
"Whenever the economy takes off, we have to work with local authorities in London and the South East to provide affordable housing," Mr Kirk said.
The NCSL will hold a conference for new heads next week, addressed by Andrew Adonis, schools minister.
It is not just teachers' passion for the classroom that can deter them from becoming heads. Many have cited the added responsibility and workload, combined with insufficient additional pay, as reasons why they do not seek the promotion.
John Dunford, general secretary of the Association of School and College Leaders, thought the future would be brighter. "The standard of the teachers coming into profession is the best ever and that augurs well for the long term," he said.