Whether they want to or not, teachers are facing the prospect of working in the classroom for longer than ever before.
The state pension age is expected to rise to 68 in the decades to come, and changes to the scheme for teachers will make early retirement less attractive, meaning that many will have to work for longer or risk losing out financially.
Now classroom unions have warned that lengthening teachers' working lives could lead to a surge in capability hearings, as headteachers try to push older members of staff - who may be struggling with the physical demands of the job - into leaving early.
The Department for Education has already commissioned research into the impact of later retirement on both teachers and students, and is considering how best to support a growing number of older teachers.
But the change in retirement age has prompted fears that teachers with prolonged working lives - who are likely to be on higher salaries than their younger colleagues - will be increasingly subject to competency proceedings leading to possible dismissal.
The state pension age is currently 65 for men and 62 for women. It will rise to 65 for women in 2018, then to 66 for both sexes in 2020 and again to 67 between 2026 and 2028. Labour and the Conservatives plan to increase it further to 68, although their proposed timescales differ.
Changes in the way teachers' pensions are calculated mean that taking early retirement will be less financially appealing than in the past. Experts have warned that teachers may be tempted to delay their departure from the profession, even if they no longer feel up to the job.
"It could mean that lots of teachers will be pushed out of the profession and we will be looking at how many teachers are dismissed on capability grounds," said Usman Gbajabiamila, policy adviser for the ATL teaching union.
"For most teachers, [the problem] is not the fact that they have to work longer, but can they work longer with the demands of the job as it is now?"
Support staff have already started taking on additional administrative tasks to reduce the workload of older staff, according to Leslie Ridings, ATL secretary for Blackpool.
"[Ministers] want teachers to work longer but they haven't found suitable employment for them to do when they get older," he said. "As you get older, it gets harder and harder to cope with a full timetable. You need to pace yourself better, but the job doesn't allow you to do that."
Fiona Barclay, 56, quit full-time teaching at Christmas when the demands of the job, coupled with caring for her elderly mother, became too much. She now teaches maths for an hour a week at All Saints Roman Catholic School in York.
"Five years ago I had a knee replacement, and even though the school was very good to me, just going up and down stairs carrying stuff was becoming too much," she said. "Sometimes I was standing and I would say to the kids that I had to sit down, or I couldn't come to them, they would have to come to me.
"My schoolbag became a rucksack that I put on my back because it was easier. But I still had one or two bags I needed to carry. There's no way I could have carried on any longer than 60. I couldn't have done it."
Chris Keates, general secretary of the NASUWT teaching union, said the shift in pension age necessitated a culture change in schools, allowing for more flexible working.
"Teachers simply cannot conceive of how they will cope for such a length of service, given the mental pressure and stress of the job," she said.
The union's internal research suggested that older teachers were particularly vulnerable to capability proceedings, Ms Keates added. "There is growing evidence that older teachers are subject to the misuse and abuse of capability procedures and find themselves targeted with such procedures as a ruse to put them under pressure to leave the profession," she said.
But Valentine Mulholland, policy adviser for the NAHT headteachers' union, said she did not expect older teachers to be disproportionately targeted for capability as a result of the changes. "I think it would be improbable that [underperforming] teachers would get to near retirement age before somebody started thinking about taking action," she said.
The DfE is commissioning two studies in response to the pension changes; one will look at the impact on teachers and their students, and the other at ways of supporting older teachers, including more part-time and flexible working.
Ms Mulholland acknowledged that school leaders did have concerns over how older teachers would cope with the physical demands of the job. "We need to look at how we can make this work for the school and, more importantly, for the children. It is an enormous challenge," she said.
`I had to get out for the good of my health'
After 32 years of teaching, Andrew Bradley, pictured, retired on his 55th birthday. At the time he was head of RE at a secondary school in Derbyshire. He now does some supply work in primary schools.
"I felt able to cope with the physical side of things, but the pressure to get results was becoming too much and I needed to get out for the good of my health," he says. "There also seemed to be a certain section within the school who were being pressured because they were old-school - because they were older teachers who perhaps hadn't taken on new initiatives as well as people hoped they would.
"I thought I could go on until I was 60 but I would probably end up living 10 years less. I knew I would be losing out with my pension but I would end up taking it for longer. I felt my health was more important."