A West Bank settler who foiled two international airport security checks by carrying a loaded gun from Israel to Hendon explained this week he was an idiot, not a criminal', whose late diagnosis with an adult form of attention deficiency disorder (ADD) cleared him of any wrongdoing.

Benjamin Lehman, 48, spent three nights on holiday at his parents' home in Elm Close in June last year, but did not notice his loaded pistol sitting in his luggage for any of that time.

Despite inadvertently smuggling his gun into the country, avoiding detection at both Tel Aviv and Heathrow airports, it was when he was leaving, on his way to a family wedding in the United States, that Heathrow security officials noticed the loaded 9mm Steyr M9 pistol in his hand luggage.

Mr Lehman, who was cleared last Thursday of two counts of having a dangerous article at Isleworth Crown Court last week, was as surprised as anyone, but said his parents, Manny and Chava, and all their neighbours had been very supportive.

"They are Jewish and understand why I needed to carry a gun in Israel," he said. "They realised they were supporting an idiot, but not a criminal."

Claiming he had forgotten to remove the pistol which he is licensed to use in Israel, as a member of a self-defence voluntary community group from one of the zipped pockets of his rucksack, Mr Lehman said last week he has always suffered from memory loss.

"I always thought my absent-minded nature was an endearing eccentric quality, rather than there being anything wrong," said the father of six, who used to live in Hendon and attended Barnet College. "I was always losing glasses and misplacing tickets, but when I forgot about the gun, that was the final straw and my wife made me seek help."

Fewer than 1,000 adults have been diagnosed with ADD (Attention Deficiency Disorder) in the UK, although it is usually associated with restless school children, of which there are 40,000 diagnosed. Little is known about the condition except that it can cause memory loss and disorganisation, and there are expected to be many more sufferers.

Mr Lehman's defence lawyer, Jonathan Goldberg QC, argued he had a reasonable excuse for forgetting the weapon as it emerged he had been diagnosed with ADD shortly after the trial started in July. This, combined with being stressed, tired and on medication for high blood pressure, led the jury to find him not guilty.

Speaking from his parents' home in Hendon last week, Mr Lehman said he was relieved the stressful ordeal of the trial was finally over', saying the stress, fatigue and lack of sleep he experienced at the time worsened his condition.

"I was at a meeting until 2am the night before, then had to leave for a very early flight the next morning," he said. "I was tired, stressed, on medication and totally forgot it was there."

"Of course I was shocked when I realised I had boarded a plane with the gun and had it at my parents' home with me, but a combination of lack of sleep and stress aggravated a condition I didn't know I had at the time," he said.

A spokeswoman for the national ADD Information and Support Service (ADDISS), in Station Road, Mill Hill, explained that 60 per cent of children with ADD will go on to have it as adults, but many do not know they have it, despite clear symptoms including short-term memory loss, impulsiveness and poor organisation.

She said: "It is often misdiagnosed as depression as the person will have problems organising their life.

"But I don't see how you can claim to have forgotten you had a gun in your bag, that seems an extreme form of ADD."

Professor Manny Lehman, a Middlesex University lecturer, said the family would now be seeking to reclaim court costs and were looking into the possibility of compensation.