According to researchers at London Metropolitan University, cover supervisors
earning as little as £6.50 per hour are sometimes asked to cover lessons for weeks at a time, despite having undergone only a few days of training.
Cover supervisors, including former soldiers and security guards, are often deployed in the toughest classes, as schools claim these are the areas where it is most difficult to recruit qualified staff.
While these temporary staff are allowed to oversee lessons when following instructions left by a teacher, the government-funded study suggests their duties often go far beyond this.
The report's lead author Professor Merryn Hutchings told the Evening Standard: "Cover supervisors were teaching - setting a task, giving advice and commenting on pupils' work.
"They are not trained or in any way qualified for that. The people we met had had careers working in the post office or being a driving instructor."
The news first came to light earlier this year when a teacher claimed schools were hiring unqualified staff as "crowd control".
Speaking at the National Union of Teachers conference in April, Andrew Baisley, a staff member at Haverstock school in London, said some schools were recruiting directly through agencies for professional doormen.
Written by Harriet McGowan