The explosion in the number of assistant heads is just one strand of a much larger debate: how big should school senior leadership teams be?

Do large leadership teams provide an effective means of developing the next generation of headteachers? Or are schools increasingly being saddled with bloated SLTs that can no longer be justified, given stretched budgets?

One individual who believes the latter is John Blake, head of education and social reform at the Policy Exchange thinktank. He claims to have witnessed SLTs ballooning in size in recent years.

“By the time I got into teaching [10 years ago], there were more people in senior leadership than I remembered from when I was at school,” Blake says.

“By the time I was coming to work for Policy Exchange [in April this year], there seemed to be more still.”

Information that could prove whether such a trend exists is not readily available, but an analysis by Tes suggests that there is certainly a significant degree of variation in the size of school leadership teams.

According to data from the November 2016 school workforce survey, The Hawthorne’s Free School in Merseyside had put half of its teaching workforce on the leadership pay range - the highest proportion for a state secondary in England. A further 10 schools were listed as having more than 30 per cent of their teaching staff in the leadership group.

At the other end of the scale, Dame Alice Owen’s School in Hertfordshire had just 3.4 per cent of its staff in the leadership pay group. Across the country, the average for all secondary schools was 10.9 per cent.

Blake says that SLT size has acquired particular relevance because of school funding pressures. He thinks schools should look at slimming down their leadership teams before resorting to other cuts.

“What I think triggers it to become a key issue is these reports from across the country of people trying to cut art projects and creative curriculum aspects,” he says.

“There’s quite a substantial amount I would cut before I cut drama.”

Losing teachers

Mark Lehain, a former free-school principal who now works as campaign director for Parents and Teachers for Excellence, also thinks some schools have “too many generals, not enough soldiers”.

As well as increasing salaries, he argues that promoting too many teachers to leadership positions incurs a number of other costs. “They generally teach less. So there’s the hidden cost of needing more teachers to backfill,” he says. “It’s silly little things like you’ll probably have an office that you didn’t have before - they soon add up. If money is really tight, schools need to look at more streamlined, lightweight leadership structures.”

However, Micon Metcalfe, a school finance director and fellow of the National Association of School Business Management, thinks that the financial cost of elevating teachers to leadership teams can sometimes be overstated. She points out that paying someone on the lower end of the leadership scale is “no more expensive” than if the individual is on the upper pay scale and in receipt of a teaching and learning responsibility payment.

Appointing someone to a leadership position also means that they are not bound by restrictions on working hours in the teachers’ pay and conditions document. “People paid on the leadership range are exempt from the 1,265 hours and the 195 days [restrictions]. You can work them a bit harder,” Metcalfe says.

So should schools be looking to cut their SLTs to unlock savings?

In a “financial efficiency checklist” published in January last year, the Department for Education listed “proportion of budget spent on the leadership team” as one of the things governors should scrutinise to ensure that schools are managing their resources properly.

However, the Association of School and College Leaders warns against making judgements based on the size of a school’s senior leadership team. “Each school has its own context and may be overseeing other schools, bringing new assistant heads on to the team as part of their professional development, or giving increased focus to a particular need,” says Geoff Barton, ASCL’s general secretary. “It’s important not to fall into a simplistic stereotype that a smaller leadership team is somehow better than a larger one,” he adds.

Metcalfe says she would encourage schools to look at the amount they spend on their SLTs - she currently provides the governors at her school with a figure for its percentage spend on leadership.

But given that information on the amount schools spend on SLTs is not routinely published, the data that schools can benchmark against is very limited. Those best placed to make comparisons are large multi-academy trusts, Metcalfe says, because they can look at the schools in their chain. “MATs could look across the group [and say], ‘This school is performing really well with a leaner structure.’”

A DfE spokesperson said: “Excellent leadership, together with high-quality teaching, is essential to improving outcomes. A supply of high-quality leaders is needed at all levels.

“Schools are best placed to manage their staffing. The fact that 1.8 million more children are in ‘good’ or ‘outstanding’ schools compared to 2010 shows that the system is working.”