With the hindsight offered by each instalment, the life paths of its participants seemed to lead ever more strongly back to their childhood desires. Among the boys was a wannabe jockey who, for a while, fulfilled the wish of his seven-year-old self. There was the shy lad who wasn't sure whether to be an astronaut or a coach driver but couldn't decide on his destination and ended up a drifter. And there was the prep school boy first pictured helping others on to the climbing frame who became a missionary teacher.
What will the boys in this picture become? Can you see a leader, his lieutenant, an outsider or a loner? Who is active and independent, a future risk-taker or adventurer? Which one is happiest to be part of a team or determined to serve others?
In a way these boys all want to be the same. They hang together like a gang, but their poses and facial expressions show that they already express themselves as individuals.
Developmentally, girls are more advanced at this age and likely to perform better at school. Boys have energy to burn off, and sitting down for too long doesn't suit them. They are leaving their mother's sphere of influence, looking for older male role models.
The effects of being left alone or unsupervised so young can be dramatic - as was so brilliantly evoked in William Golding's novel The Lord of the Flies, Rudyard Kipling's Jungle Book and the film Stand by Me.
Play is an instinctive way of interacting with the world, of making friends, of fighting with and looking after each other. As reliance on adult carers recedes and before romantic attachments are formed, friendship becomes increasingly important. Mates are what matter. Peer pressure gets the blame for many ills, but it has a positive side, and the sense of kinship between kids can last a lifetime.
The phenomenal success of the Friends Reunited website proves that memories of childhood friendships can leave a deep impression on our adult lives. Set up on a hunch that people might like to get in touch with school pals, it is the most visited website in the UK and has made its creators millionaires.
As adults, when we say something is child's play, we mean it's easy, insignificant even. But play is an education in itself - even if you can't measure it or test it.
When we were their age, we learned about the world, how to socialise and have fun, simply by messing around. And when we grow up, we don't totally abandon childish ways. The way we were raised, and the way we played aren't just part of the past. They made us what we are today. Photograph by By King Tuang Wong.
Weblinks Lord of the Flies: www.gerenser.comlotf Find your old friends on www.friendsreunited.co.uk Seven Up documentary series: http:web.ukonline.co.ukott sevenup.htm This picture is part of a series published in Friendship: a celebration of humanity, by the MILK project (Hodder Headline pound;30)