The new teachers at Ashcombe school in Dorking, Surrey, had to avoid contact with students while they waited to be vetted. They were escorted on and off the site by other teachers. They were kept busy in the staffroom, marking work and writing lesson plans.
The 1,500-pupil comprehensive had been forced to send home more than 500 of its Year 8 and 9 students because of the delays at the Criminal Records Bureau.
Arthur Webster, headteacher, said: "We wanted our new teachers in the school sooner rather than later, but we are having to hide them so they do not talk to pupils, and they eat lunch separately.
"Nearly all of our NQTs were in other schools last year on teaching practice, and many were unchecked. I would like to know how many NQTs were shown by the checks last year to be child molesters."
Newly-qualified maths teacher Ian Robson, a former city trader, said he felt frustrated that he could not teach his class.
"At least there are 15 of us in the same situation," he said. "If it was just one or two of us there would be a stigma, and the pupils would be wondering why we needed such long checks."
Ashcombe School went directly to the Department for Education and Skills'
child protection group for its advice. This has now changed because of ministers' U-turn this week (see story, left).
But other schools in Surrey had already been allowing teachers whose checks were pending to work. They had been following guidance from the local council, which told heads they could take staff who had an unbroken service record or had police checks during their teacher training.
At Cockburn high in Leeds, headteacher Colin Richardson had 12 staff still waiting for clearance when term began on Wednesday. They can now teach after a fast-track check, but even if official guidance had not changed, he would still have let them teach.
He said: "Most years we would not have found the results of the checks until half-way through the autumn term. My view is that my kids are not at risk inside the school, but they are at risk outside it."
He added that any uncleared teachers would be monitored by department heads until their clearance arrived.