The best of the UK’s private schools enjoyed some well-deserved recognition last week.

But behind the glitz and glamour at the Tes Independent School Awards conversations were taking place that laid bare the vulnerability that the sector currently feels.

It may have been spared the prospect of “integration” into the state sector under a Labour government (although there are fears that a Tory party keen to appease its new northern, working-class voters may not be the ally it once was).

But there is a much more immediate problem. Growing numbers of teachers in independent schools are unhappy about being removed from the Teachers’ Pension Scheme (TPS) and being offered what unions say are “less favourable” alternatives.

Exclusive: Schools hit by ‘devastating’ rise in pension costs

Opinion: Private schools are a canary in the pensions mineshaft

Quick read: Private schools could have ‘phased withdrawal’ from teacher pensions  

The issue stems from the need for a 43 per cent increase in employer contributions to the Teachers’ Pension Scheme. The government is covering state schools for the rise - for now at least. But independent schools need to either find the money themselves or to pull their teachers out of the scheme.

Teacher strikes over pensions

And with margins at many independent schools tight, some are going for the latter option. But their teachers, unsurprisingly, are not always keen.

Staff at The Grange School, in Cheshire, and at Westholme School, in Lancashire, have each recently voted to strike over governors’ plans to remove them from the Teachers’ Pension Scheme. So are these just one-offs or is the problem going to get bigger?

“I wouldn’t be surprised if there’s more industrial action,” says David James, deputy head of Bryanston School, who has warned that the issue is one of his sector’s “biggest challenges” in years.

“But what is key is that schools work very closely with staff on any possible changes and be transparent,” he says.

Being transparent could mean governors of schools, especially the smaller ones, explaining to teachers the economic hardships they may be under and the difficulty in finding the money for that whopping 43 per cent hike in contributions.

In smaller rural schools, already under pressure from rising teacher pay, could it be a case of teachers accepting that they either come out of the TPS or lose their jobs?

“For a long period of time teachers have benefited from a pension scheme which is eye-wateringly great,” says Mike Abraham, director of independent school leaders’ consultancy Heads for Heads.

“But it wasn’t part of the real world. If you make a comparison with industry and business then teachers have had a really good deal, and there had to be some balancing up.”

But the truth is that teachers in state schools will continue in the TPS, so is this fair?

One knock-on effect, the NEU teaching union has warned, is that this could prevent independent schools from attracting talented teachers.

James says “the right position” would be for schools to consider how they can make savings elsewhere and other revenue streams before removing staff from the TPS. He argues that: “Any strike would be a failure on both sides.”