The head rose from her chair and fixed both boys with the full force of her X-ray vision. Then she waited while the big clock ticked away the silence (and lunchtime) like the metronome of truth.
Let them squirm for a while, it's what they deserve.
When, finally, she spoke, it was in a voice so latently wrathful, so witheringly disdainful, so coldly disappointed, so vintage Margaret Thatcher teaching her Cabinet the error of their ways, that they could not help but sob quietly to themselves.
A few streaky tears would at least go some way towards helping them realise the enormity of their crime. Oh yes, it would be a quiet day in the dining room before they ever contemplated locking someone in a stock cupboard again. Especially when that someone happens to be their teacher.
It's no fun being locked up in a confined space, particularly when you are borderline claustrophobic on account of a childhood experience at a fancy dress party. (Be warned: if you are ever tempted to wear an all-in-one Dalek outfit constructed by your dad, think again. Or at least ensure it is adequately ventilated and easy to escape from.)
Claustrophobia is more common than you would think. It is an anxiety disorder suffered by about 10 per cent of the population. This means that there is a large number of teachers out there who can imagine exactly what it must feel like to be locked in a stock cupboard: that sudden sense of suffocation, that feeling of being unable to escape confinement, of being trapped with the ghosts of 1,000 dead worksheets, faded lesson plans and teachers' toolkits still shrouded in cellophane.
A programme of desensitisation is the recommended cure for most phobias, but this was the cold-turkey version. For 15 minutes, the pitiful sounds made by a grown teacher yelling, pleading and crying like a baby went ignored. The claim is that no one heard. But really, in a busy school like ours? Rather unlikely, I would have thought.
"Now, while you're here," says the head to the teacher, after the boys have mumbled their apologies and shuffled away, "I want to talk to you about something else." She closes the door with a firm click, resumes her seat and eyes the abused member of staff.
Sometimes teachers need to squirm for a while; it's what they deserve.
When, finally, she speaks, it is in a voice so calmly reasonable, so gently reassuring, so benignly amicable, so David Cameron with an arm around Nick Clegg, that the sense of fear becomes almost palpable.
"It's about the fact that you still haven't updated your long, medium and short-term planning files; implemented the new marking scheme; uploaded your half-term assessments; improved your classroom environment; made sure your working walls are up to date; up-skilled yourself with the latest interactive whiteboard technology; organised your continuing professional development folder; implemented the latest policy changes; attended several after-school training events ... Where are you going now? ... Come back immediately! ... What do mean, you're going to lock yourself in the stock cupboard?"
Steve Eddison is a KS2 teacher at Arbourthorne Community Primary School in Sheffield.