It’s a Boy’s Own gift that will be stuffed into thousands of Christmas stockings, but a retired brigadier has discovered that the credit card-sized toolkit — complete with 5cm (2in) blade, compass, tweezers and toothpick — could put the recipients on the wrong side of the law.

Tom Foulkes, 56, who spent 35 years working for the Ministry of Defence developing real weapons, was arrested, locked up and had his fingerprints and DNA sample taken after the kit was discovered in his overnight bag by police.

The former Royal Engineer was preparing to board a Paris-bound train at Waterloo when an X-ray machine alarm was triggered by the toolkit. He was hauled from the station, placed in a cage in a van and taken to a police station for questioning. Four hours later he was released and cautioned after admitting to possessing an offensive weapon; Mr Foulkes had seen it as something with which to sharpen pencils and cut off luggage labels, and that his wife occasionally used to pluck her eyebrows.

Mr Foulkes aired his grievance in a letter to The Times. Yesterday he revealed more about his ordeal. “The whole thing was an absolute farce,” he said. “I’m now on the police database. They have photographs of me and records of my DNA and my fingerprints, all because I was carrying this useful little tool.”

Now director general of the Institution of Civil Engineers, Mr Foulkes was on a business trip to Paris when the officers arrested him. “I was bundled into the cage of a police van and taken to Tottenham Court Road custody centre,” he said. “My former rank seems to be the only thing that saved me from being handcuffed.”

The “multitool” was sent to a knife destruction centre in North London.

Mr Foulkes has now written to the Chief Constable of the British Transport Police to express his concern. “I want him to tell me if he thinks it is a sensible use of his officers’ time,” he said. “Surely they are trained to use some discretion and could see that I wasn’t a threat to anyone?

“I travel all over the world on business, to places such as Pakistan and parts of Africa, where a little tool like this is invaluable. If I had accidentally packed it in my hand luggage, airport security would probably have just taken it out of my bag and thrown it away and I’d be on my way. I can’t imagine that I would have been arrested.”

The transport police said that the officers used their discretion during the arrest and deemed the gadget to be a concealed weapon, prohibited under the Prevention of Crime Act 1953.

Mr Foulkes, who lives with his wife, Sally, in Fleet, Hampshire, is annoyed that he did not stand his ground over the issue. “I was polite throughout the experience, but after the event I realised that the right way of dealing with it would have been to say, ‘I’ll see you in court’, and to have argued it out there, instead of accepting the caution. The whole thing took up about four hours of police time. I dread to think what that cost the taxpayer.”

How the law defines offensive weapons

Source: The Home Office

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