Smelly. Vile. Disgusting. All these words can be used to describe the people found in schools the length and breadth of the country.

Teachers, that is. Not students. Teachers. As much as they would deny it until they are hoarse, it seems that a great many teachers have repulsive personal hygiene and habits that would make any clean-living soul feel ill.

Paranoid?You should be. There’s only one way to hear the unpleasant facts - you have to ask the students. I did. And there’s no reason to believe that our focus group of five south London teenagers were telling anything but the truth about the teachers they have encountered during their academic careers.

They don’t cough up that easily. They were terrified that their comments would come back to haunt them. Isabel and Malika were particularly worried - their teachers are nuns and, apparently, have a direct line to the Vatican.

But when they pluck up the courage to tell me their olfactory tales, the truth does make you feel sick. The first thing was a complaint about bad breath. You’d think that teachers might pop a mint or brush their teeth before leaning over their students’ shoulders, but it appears that many don’t know the first thing about oral hygiene.

Halitosis is often caused by a failure to brush the tongue as well as teeth, but the students reported close encounters in the classroom with cigarettes, coffee, food with strong flavours, even alcohol.

Gustavo mentions his science teacher, whose breath, in a word, “stinks”.

His solution to the problem? “They should be made to bring a box of Tic Tacs with them every day.”

Despite its malodour, bad breath can only be smelt and not seen.

Unfortunately for the millions of long-suffering students in Britain, the same cannot be said about flaky skin. The most common is dandruff. I’ve been told tales of teachers who fail to notice flakes on their shoulders or - worse still - sit at their desks furiously scratching their scalps oblivious to the cascade of flakes they are generating.

Even teachers who teach hygiene can be grubby. Malika has a particularly horrifying story about her food technology teacher, who once scratched her head before kindly offering to help Malika knead her pastry.

Aisha can top that, though. One of her primary school teachers suffered from dry skin on his legs. Whenever it became itchy, he’d hitch up his trousers, lower his socks and scratch away, leaving a lovely pile of flaky skin on the carpet. Aisha once described his habit to another teacher, whose reply was: “Nasty.”

Some teachers are reluctant to bathe before going to school. As Stephen points out, teachers would be upset if they knew students didn’t make the effort to get wet and waltz some shower gel over themselves in the morning, so they have every right to take offence if the shoe is on the other foot, to mix the metaphor.

Once started, the teenagers were keen to let rip on other deeply annoying things about their teachers. But another time.

Chris Johnston was talking to Isabel Weston, Malika Quintyne, Aisha Abubakai, Gustavo Silva Navarro, all aged 13, and Stephen Adu-antoh, 15, who attend New Peckham Varieties children’s theatre group in south-east London