Leadership is about - or should be about - vision, boldness and managerial talent. For many it is also about being committed to seeing the job through. But how long should a school leader remain in post? One headteacher of a school in Somerset is promising five years.

Though some heads exit early through ill-health or a bad Ofsted, most leave their school at a time of their choosing - and if that chance comes early, perhaps with the offer of a better job, what happens to those left behind?

When Andy Russell arrived at Wyvern school, in Weston Super Mare, in September 2004, the place was a victim of revolving head syndrome. Wyvern, a mixed 11-16 comprehensive with about 900 pupils, was in crisis. Four headteachers had come and gone in as many years.

One former acting head had developed a plan for recovery. Mr Russell might have been tempted to ride the wave and claim the credit for the restored order and improved exam results before de-camping and moving elsewhere. But on his first full day, Mr Russell vowed publicly to stay put for five years.

Exam results at the school offered some hint of potential for better days.

“We’d gone from 22 per cent to 35 per cent of pupils getting five A*-C grades at GCSE,” he said. “We could tell children that they were in the most improved school in north Somerset. That’s when I first started saying, ‘I’m going to be with you for five years.’ I think that was important, and it’s something I’ve reiterated to children and parents.”

When talking about the effect of short-term heads, Mr Russell draws a cricketing analogy.

“When one leaves, it’s like losing a wicket and seeing the run rate slow down,” he said.

“If Wyvern is to be the best school in Weston, I’ve got to stick around to make sure things can become embedded.”

Certainly, Mr Russell has made a big impression on his deputy head, Paul Ryan. “If you say you’re here for the long haul, then others say, ‘I’m going to get on board,’” Mr Ryan said.

Lesley Howson, an advanced skills teacher who has been at Wyvern for 12 years, says staff at the school are now much clearer about expectations.

“His commitment has brought stability in the community,” she said.

Mr Russell clinched the head’s job during a “trial by tea party”. But his promise to stay for five years did the trick.

“He said, ‘If I haven’t done the job in that time, then I’m not fit to be here,’” said Char Tucker, Wyvern’s chair of governors.

“My view is, he was putting his career on the line - he had to make it work.”

Tellingly, few staff will leave the school this year. “A couple had interviews at other schools but have withdrawn their applications,” said Mr Russell.“I think that reflects that people are content to stick around.”

Importantly, all of his senior management team are still in place.

“In the football world, you have fixed contracts - three to five years - and I wonder if that would be a good idea with headships: a minimum-term contract rather than fixed-term,” he said. “It would show commitment to the governing body who appointed you.”

Toby Salt, strategic director for leadership development at the National College for School Leadership, says sustainable change is important.

“You can have an impact on some things - such as behaviour - quite quickly, but fundamental change takes time,” he said.

“We need to beware the danger of quick wins - the effects of the hero head are too short-lived - and focus on strategies for long-term gain.”

In any case, Mr Salt believes success should not depend entirely on the head. “Heads need to create a network of distributed leadership,” he said.

“This also takes time but means that when they leave, the foundations will be secure.

“It will help with recruitment as the prospect of moving into leadership roles will be far more appealing for teachers. Instead of starting from scratch, they’ll be able to build upon what is already in place.”

Mick Brookes, general secretary of the National Association of Head Teachers, was head of Sherwood junior school, in Nottingham, for 20 years.

“Schools need periods of stability, but I wouldn’t discount the effect on a school in difficulties of a good fixer - a head who comes in to sort out a specific job,” he said.

“But someone who is a catalyst for change may not necessarily make a good maintainer. Schools, teachers and parents like stability, and the disruption caused when a head leaves can be significant.

“However, I think minimum contracts would be difficult to enforce. There is also a downside of people being too long in the same place.”

Peggy Farrington, head of Hanham high, near Bristol, an 11-18 school with 1,600 pupils, has been in post for seven years and always intended to stay for at least five. She arrived to find a pound;146,000 budget deficit along with poor attendance and behaviour, a downward spiral in exam results and no satisfactory relationships with partner schools.

“Long-term commitment depends on the situation you find yourself in,” she said. “There’s never a good time to go - there’s always the next Ofsted, for instance.

“I’d have been uncomfortable making a bid for specialist status (in performing arts) and going off before I’d seen it through. You have to think about sustainability if you’re to get the community behind you.”

She has been down a tough road to improve things but doesn’t believe that minimum contracts are always the answer.

“If a head joins a school where all’s going well and just needs to change things a bit, then a long period there may not be necessary,” she said.