FAR from being hapless eccentrics, the majority of people who stalk royalty have a serious psychotic disorder. The discovery has been key to reducing the risk of attacks on the British royal family, and British and European politicians.

Paul Mullen, a forensic psychiatrist at Monash University in Melbourne, Australia, and his colleagues looked at records held by the Metropolitan Police in London on 250 people who had stalked members of the royal family between 1988 and 2003.

Of these, the team reckons about 80 per cent show symptoms such as hallucinations and delusions that are typical of people with schizophrenia.

The findings, known for two years, were made public this week at a forensic science meeting in Melbourne. They show that royal stalkers are clearly different from those who stalk ordinary people, who tend to be depressed, socially inept rejected lovers.

In the past, royal stalkers who were causing a nuisance were merely removed from the scene. Now mental health professionals from the Fixated Threat Assessment Centre (FTAC), which was quietly set up two years ago by the UK Home Office, assess the stalkers and refer them for treatment if necessary.

In the past, stalking behaviour was typically repeated. "Now that they are treated it is not," says David James, clinical director of the FTAC. Few VIP-stalkers go on to commit an attack, but when they do, the attacks tend to be serious.