I first joined Mensa, the high IQ society, when I was 23, and attended some of its local meetings. One of the society's aims is to provide a forum in which people with high IQs could meet and talk rationally about intellectual matters. To become a member one has to score in the top 2% in a monitored IQ test, which is not all that exclusive, given that over a million people in the UK could qualify.
I let my membership lapse, and only rejoined over a decade later when I returned to the UK. Many of the London meetings were quite ordinary affairs, with perhaps a dozen or so members meeting in the upstairs rooms of pubs to discuss current issues. At some of these meetings I befriended Victor Serebriakoff, its chairman, and Clive Sinclair, the inventor. I was asked by them to stand as Secretary with their backing, and was elected. Clive Sinclair became its chairman, with Victor moving up to the post of President of International Mensa, and the three of us acted in concert to improve the society.
We introduced a colour magazine to replace the rather tatty "yellow pages" that announced club meetings. We staged upmarket events like black tie dinners, introduced a lecture series featuring well-known authors and academics, and staged a residential "Mensa at Cambridge" each year. We also recruited members by advertising Mensa tests in newspapers. Gradually the numbers increased. During the 13 years in which the three of us constituted its top officers, UK membership went from under 2,000 to just shy of 40,000.
I tried to leave the committee several times, but was persuaded to stay on and keep the team together. Finally I managed to leave because I contrived to be in the US at the time nominations had to be submitted. I thus left the committee, and allowed my membership to lapse shortly afterwards.