Transportation to Australia was undoubtedly a grim experience for 18th and 19th century convicts, many of whom had only committed petty crimes in Britain.

But a new study has shown there was one unexpected benefit from the dubious practice: happier marriages that have lasted to this day.

According to researchers of the University of New South Wales, so many men were sent to Australia that it dramatically altered the sex ratio between men and women.

As a consequence, women were prized and so could choose better husbands who were more capable providers and were less likely to stray.

It meant both sexes enjoyed marriages that were stronger, stable and happier and fostered a highly-respectful attitude towards women that has lasted more than 150 years, the authors conclude.

Dr Pauline Grosjean, Associate Professor, of the School of Economics from the University of New South Wales, said: “This inadvertent sociological experiment changed mating market conditions.

“We find that both men and women are happier, and the happiness gap within married couples is smaller in areas where convict-era sex ratios were heavily male-biased.

“One interpretation of this result is that because women have higher bargaining power they are more picky and search for a better match, and as an indirect effect, those men who do marry also benefit from this better match quality. A second possibility is that married men’s happiness is contingent on the happiness of their wives.