The explanation for the preference is not clear, but experts in human evolution say that facial hair may be a signal of aggression because it boosts the apparent size of the lower jaw, emphasising the teeth as weapons.

Psychologists at Northumbria University who carried out the new study believe that stubbly men may offer women the best worlds - not too strongly masculine, but mature and with the potential to grow a full beard.

The researchers carried out the study using computer technology to alter pictures of 15 men's faces so that they displayed different degrees of hairiness - clean-shaven, light stubble, heavy stubble, light beard and full beard.

Faces with full beards were judged to be the most masculine, aggressive and socially mature. They were also thought to look five years older. They were rated the least attractive and the worst choice for a short-term relationship.

Men with light beards were considered the most dominant. Those with light stubble were rated the most attractive and as the ideal romantic partner for the short or long term.

Clean-shaven men finished bottom for masculinity, dominance, aggression and social maturity, and they were the least favoured choice as a long-term partner. They came second-to-last for attractiveness.