Yet this is what happened when he travelled back from a business trip to the Turks and Caicos islands via New York on 22 May. Still traumatised by his ordeal, the 47-year-old is furious that the airline failed to protect him from the gung-ho actions of an over-zealous passenger who claimed to be a police officer. He has now instructed a team of top US lawyers to act for him.

The London-based interiors guru, whose clients have included Peter Mandelson and the husband-and-wife design team Suzanne Clements and Ignacio Ribeiro, said he felt compelled to speak out to protect other innocent travellers from a similar experience.

"This man could have garrotted me and what was awful was that one or two of the passengers went up afterwards to thank him," said Mr Stein. He has since been told by airline staff he was targeted because he was using an iPod, had used the toilet when he got on the plane and that his tan made him appear "Arab".

"I was terrified but am fortunate in that I was able to contact a lawyer. Yet someone else who is not assertive could be left completely traumatised."

The incident highlights the increased likelihood of innocent passengers being picked on because they are perceived as "suspicious" or "foreign-looking", especially following the alleged plot to blow up airliners with liquid explosives.

Earlier this month, a plane from London to Washington DC made an emergency landing, escorted by fighters, after passengers alerted crew to the behaviour of a female traveller. It later emerged she had suffered a panic attack. And in August, two innocent Asian students were escorted off a flight from Malaga to Manchester because other passengers thought they were terrorists.

In Mr Stein's case, he was pounced on as the crew and other travellers looked on. The drama unfolded less than an hour into the flight. As he settled down with a book and a ginger ale, the father-of-three was grabbed from behind and held in a head-lock.

"This guy just told me his name was Michael Wilk, that he was with the New York Police Department, that I'd been acting suspiciously and should stay calm. I could barely find my voice and couldn't believe it was happening," said Mr Stein.

"He went into my pocket and took out my passport and my iPod. All the other passengers were looking concerned." Eventually, cabin crew explained that the captain had run a security check on Mr Stein after being alerted by the policeman and that this had cleared him. The passenger had been asked to go back to his seat before he had restrained Mr Stein. When the plane arrived in New York, Mr Stein was met by apologetic police officers who offered to fast-track him out of the airport.

Mr Stein said: "The other passengers looked and me and said, 'What did you do?' It was so humiliating. The fact is he [the police officer] was told I was OK and should have left me alone. The airline had a duty of care. I've got to travel to the US soon, but I'm paying an extra £500 to travel in business class."

American Airlines apologised to Mr Stein, who was born in New York, but withdrew an initial offer of $2,000 compensation on the grounds it would be an admission of liability. In a letter dated 30 May, the airline said it had done everything possible to try and protect Mr Stein.

It read: "Unfortunately, as in any public gathering, there may be occasions when a conflict arises between people or when one individual's actions bother another... As our crew members may not always be witness to the inappropriate acts of a particular passenger, there may be a limit to what our crews can do to improve behaviour that is perceived as a nuisance."

In a twist to the story, Mr Stein has since discovered that there is only one Michael Wilk on the NYPD's official register of officers, but the man retired 25 years ago. Officials have told the architect that his assailant may work for another law enforcement agency but have refused to say which one.

Sophie Goodchild, The Independent