London: When his young sons wanted to give the family boat a "silly name", Laurence Godfrey was happy to let children be children.

So the four metre motorboat was proudly hand-painted with the name Bin Laden 1 by his son Dylan, then aged 11. He had heard the name on TV and thought it was funny.

But the boat named as a joke after the Al Qaida leader has suddenly attracted the attention of police and the Ministry of Defence.

Dr Godfrey says he has been told he must change the name because it could allegedly cause a threat to security at the Olympics.

Despite the family using it for two years without complaint, they were stopped by police after landing at Greenwich Yacht Club following a trip on the Thames last weekend.

Physicist Dr Godfrey had taken his son Waylan, six, Dylan, now 13, and Dylan's 13-year-old schoolfriend along the river to see Tower Bridge.

"Until they started shouting at me I assumed [the police boat] was nothing to do with me," he said.

"The first question they asked me was, ‘Why did you call the boat Bin Laden? I said, ‘You better ask my child because that's who named it'."