Nick Clegg has been given a pre-election boost after psychological research showed the Liberal Democrat has four of the five key personality strengths of a "perfect" leader.

Professor Alex Linley, director of the Centre of Applied Positive Psychology, said all three party leaders showed "promise" in terms of judgment, compassion, personal responsibility, tackling problems and seeing how things can be improved.

Gordon Brown was perceived to be good at tackling problems head-on and sorting them out, David Cameron's main strength was optimism, maintaining a positive outlook, while Mr Clegg was said to have accurate judgment, was compassionate and a "born improver".

Professor Linley said the results of his research were "surprising", adding: "Nick Clegg is rated extremely highly, despite his relative inexperience. For example, people have rated him as having high levels of judgment on decision-making, even though he's untested.

"These results demonstrate that modern day politics isn't just about policies, it is about people's perceptions of the politicians who will lead us.

"Brown is tried and tested so people are more likely to be able to analyse their strengths accurately and appropriately, whereas Cameron and Clegg are relatively untested with unknown quantities. What remains to be seen is whether people will take the risk of the unknown and go with the 'perfect' PM Clegg."

The report was based on a study of 235 people with an interest in strengths and positive psychology.