Good-looking political candidates are more likely to win elections – particularly in marginal seats.

New research from the Universities of Exeter and Iowa shows the appearance of a candidate becomes more important once most other variables are eliminated.

"While our findings certainly do not indicate that unattractive candidates are unelectable, they do suggest that an attractiveness 'advantage' may come into play," politics lecturer Caitlin Milazzo said.

"As a result, parties should be mindful of the appearance of their candidates, particularly when contesting a marginal seat."

"If you imagine all other things equal then this will give you the edge."

Seventy-five pairs of same sex, same race candidates from the 2010 British general election were selected by Milazzo and shown to volunteers in the US, who were then asked who they found most attractive.

Attractiveness correlated to victory only about half the time, but shot up to 72% when marginal constituencies were involved.

The results suggest that attractiveness only plays a key role when party allegiance is lower and candidates are less well known.