A real friend, one who will remain loyal and dependable through thick and thin, is much more likely to be a woman than a man, according to researchers in Manchester.

Their study seems to establish what women have always known — that men are fickle things who are in it for what they can get. Analysis of the behaviour of 10,000 people identifies the friendships made by women as being far “deeper and more moral”.

Women are genuinely interested in their friends and want to know what they are doing, how they and their families are getting on and how they feel. The fickleness of men is reflected in the finding that their choice of friends is far more likely to be based on a calculated element of self-interest. They are also most likely to make friends through a mutual interest in a drink at the pub, but even then their eye is always on what the friends can do for them.

“Friendship between women seems to be fundamentally different from friendship between men,” Gindo Tampubolon, who led the research at the University of Manchester, said.

Although both genders exhibited selfishness and altruism in friendships, men displayed more “me, me, me” characteristics, he said.

“Friendship is much deeper and more moral for a woman. Women tend to keep their friends through thick and thin, across geography and social mobility. Men, on the other hand, are more fickle with their relationships and seem more interested in asking, ‘What’s in it for me?’ ” The strain placed on friendships by house and work moves that increase geographical distances is far greater for men. Women are likely to try to keep in contact with old friends, however far away they may be, but men can be expected to start again by making a fresh set of acquaintances, especially when they are able to meet them over a pint.

The biggest strains on friendships are when one or another of the friends gets married, divorces or is widowed.

Getting pregnant or having a child is another prime cause of “ruptured friendships”, as is having a child move to a new school.

The pattern of friendships was identified in a study of data collected for the British Household Panel Surveys from 1992 to 2002.

The researchers found that the middle classes were likely to cast a net of friendship over a greater gulf of social class than other socio-economic groups. Working-class people had the largest proportion of friends from the same social background. The study also revealed that 25 per cent of people have best friends from the opposite sex.

Mike Savage, a professor of sociology, said: “This research draws upon a tradition of inquiry known as social network analysis, developed by Professor John Barnes, based at the Victoria University of Manchester in 1952-53.

“SNA is able to analyse social structures using a series of algorithms and we wanted to explore its application in this area and others.”

Times Recommends

• The bright side of this winter rain
• Story behind the picture: Snow Leopard, 2008
• Times Charity Appeal: The Place2Be