The problem for any modern day politician is that they need to come to the job with no past, as any form of past could be used against them. Most of the time we should pity the politician, at other times burying parts of their history may well be strategic.
David Cameron is inventing himself as a new, 'green', family man, just an ordinary guy with the same cares and concerns as the rest of us. This brackets off his very privileged upbringing and his membership of one particular group for ultra-rich toffs. The Bullingdon Club is a socially exclusive student drinking society at Oxford University, infamous only for its members' wealth and destructive capacity. Membership is by invitation only, and prohibitively expensive for most. The Club was founded over 150 years ago, originally as a hunting and cricket club but now exists primarily as a dining club with a vestige of hunting in the support of the point to point. The club traditionally meets for an annual breakfast at the Bullingdon point to point, and a club dinner, as well as smaller initiation dinners, before which the rooms of new members are wrecked.
As the above picture shows members, the pictured includes Cameron, 2nd along the back row and Boris Johnson, front right seated, traditionally dressed for their annual dinner. The event they are going to would find them booking a private dining room under an assumed name, then physically destroying the place. Very large amounts of cash are then offered to the owners to pay them off for the destruction. The Bullingdon Club is satirised in Evelyn Waugh's novel Decline and Fall (1928), now why do you think that nice and ordinary Mr Cameron tried to restrict access to and publication of this photograph. What perception does this offer of him and his background, how authentic does he appear?