What is more dangerous than living in a war zone?

Prince Charles and Prince William, the second-in-line to the British throne, should be beware, as a new research has found that being a monarch is more dangerous than living in a war zone.

The Cambridge University research that looked back on the lives of more than 1,500 European kings and queens found that more than 20 per cent of them died a violent death. That is four times more likely than a soldier in a war zone and 200 times more likely than those living in Cuidad Juarez -- the Mexican city with the highest murder rate in the world, the Telegraph reported.

Study author Manuel Eisner, a professor in criminology at Cambridge, found that the biggest cause of death was rivals taking the throne, followed by battles with neighbouring monarchs and revenge.

A few kings and queens were killed by random members of the public who had a grievance with authority.

Often murder would beget murder with a number of murder hot spots, he found. According to the researcher, 15 out of 17 monarchs between 889 and 1094 in Scotland met violence deaths while 14 out of 15 Northumbrian monarchs were murdered in the 8th century.

"It was a very dangerous occupation but the good news is it has become a lot less dangerous in the modern world," said Professor Eisner.

"This (murder) rate is higher than the threshold for 'major combat' among soldiers engaged in a contemporary war. It demonstrates the intense violent rivalry for domination among historical European political elites," he said.