This post is exempt from the provisions of the Rehabilitation of Offenders Act 1974...you are required to complete as a part of your application for this post an enquiry from (PROT 5) giving details of any: 1. Convictions for criminal offences 2. Bindover orders or cautions...

The statement on the end of every application form for a teaching post has never bothered me - until 10.30 one morning.

“Mr Cosgrove? We have your son in custody.”

This is the call every parent dreads. Drugs? GBH? Joyriding? Tom had left home at 7am, cycling shakily down the road, the surfboard strapped to his back giving him all the grace of a poorly co-ordinated Teenage Mutant Turtle.

Subdued, he sat opposite me in a bleak interview suite: “They took my laces.”

He and a friend had gone to their favourite surfing spot, near the harbour, and had painted on the wall in giant letters: “LOCALS ONLY”. No drugs, no violence, No real lasting harm done...except to Tom.

He was read his rights; the duty solicitor came. The interview was taped. Statements were signed. He was finger-printed. By the time they gave him his laces back, he was one thoroughly cowed Teenage Mutant Zenophobe.

Tom wanted to go straight back and remove his handiwork, but the regulations didn’t permit it. Instead he cleared out his savings and paid the council’s contractors to do it. And there matters rested. For three months - until we were once more summoned to the police station.

Before deciding whether or not to prosecute, the police at times offer a caution. By admitting guilt and expressing remorse, an alleged offender can avoid a criminal conviction, although the caution remains on record.

The council said they did not want to prosecute. If Tom turned down the caution, in all likelihood the matter would be dropped. But what if it wasn’t? What if the Crown Prosecution Service ignored the council’s wishes? We took the caution.

If ever my son wants a job in teaching, youth work, child care, or any other career giving substantial access to children, if ever he applies to foster or adopt, he must admit to a caution for “criminal damage”. This, we are told “may not necessarily debar you from the appointment”. The application may not go straight in the bin, but it will end up at the bottom of the pile. Now and for the rest of his life. A high price to pay for Teenage Mutant Zenophobia.

John Cosgrove is a deputy head in Cornwall.