The Green Diamond Club – affectionately known as the Gee Dees – was formally started in 1957 by Peter Hammond, who until 1995, was the Chairman of the club. The Green Diamond symbolises peace and international friendship stretching to the four corners of the earth. 

In 1954, Peter organised a ski trip to Seefeld, Austria, costing just 29 guineas for 15 days (which included the rail and boat fare, heating fees, kurtaxes and a 10% service). This trip was so successful that it became an annual event, and formed the basis of the Green Diamond activities. Memories of the Second World War were still fresh in people’s minds, and Peter’s objectives were to organise activities suitable for parties rather than individuals, to promote a spirit of friendship extending where possible to International Relations, to provide a means of charitable contribution and to support the United Nations Association. 

In 1957, it was decided that meeting only once annually was simply not enough, and this was when sailing was established at Chichester Harbour, costing just £1 for a whole day of sailing, including transport from London. In 1959, the first dinghy was bought for £60 and sold a year later for £65. Sailing developed rapidly and the fleet was gradually enlarged and replaced with better boats. 

Water skiing began in 1963 with a small outboard ski boat on the River Hamble, where it continued until a 4mph speed limit was imposed. It moved via lakes at Oxford, Tallington, Cosgrove, Berinsfield and to its present home in Chichester. 

In 1960, membership subscription was 5/-d per annum, and by 1962 the club had 62 members (up from the 6 in 1957). 
By 1965, the club owned 3 sailing boats and had a speedboat at its own exclusive disposal. This was the year of rejuvenation for the club; the year to encourage 20-25 year olds to join the club. 

The club made continued progress in financial strength and improved activities. In 1969, Peter Hammond entered the Daily Mail Transatlantic Air Race from the top of the Empire State Building, in New York, to, what was, the GPO Tower, in London, by scheduled aircraft. On the strength of members’ connections with British Airways, GPO, PLA, the Police to name a few, Peter was able to go on and win the Rothman Trophy, for the fastest journey by subsonic aircraft, and a sum of £4,000. He entered the race twice and in his second attempt he managed to clip off 56 seconds off his time, meaning his winning time was 6 hours 54 minutes. With the winnings, the first canal cruiser was bought.