Half of the group went to fight in WWII and the other half came from one of Boston’s most disadvantaged areas at that time.

All men were surveyed every two years and underwent medical exams.

Professor Waldinger of the university discussed his findings at a recent TED talk, and revealed that strong relationships are the most important factor when it came to happiness.

“The clearest message that we get from this 75-year study is this: good relationships keep us happier and healthier: period,” he says.

This is the optimum age for happiness in the UK