A selfie? On Cameron and Obama's part, this memorial snap was just plain shabby

I can't be the only person over 30 years of age who found the picture of David Cameron, Barack Obama and the Danish PM, Helle Thorning-Schmidt, taking a “selfie” at Nelson Mandela's memorial service profoundly depressing.

There they are, two of the world's great leaders - and David Cameron (sorry, couldn't resist it) - huddling together like teenagers at an Olly Murs concert. On the one hand, it made them look like real people - who wouldn't want photographic evidence of being seated between the US President and the British Prime Minister? - and this was very much the line adopted by Ms Thorning-Schmidt.

She said it proved the three leaders were indeed “just people who have fun”. She added: “It wasn't appropriate. There were lots of pictures taken that day, and I just thought it was a bit of fun.” There we were, thinking that the death of the greatest world figure of all our lifetimes was a time for sadness, reverence and contemplation, but actually it was an occasion for a bit of harmless photograhic braggery that might, all things being equal, go viral. So, less about self-reflection, more about the selfie. In fact, it's all about self these days, and it's this I find so depressing.

It used to be the case that, if you were at a big occasion - a concert or a sports event, say - you'd pay full attention, experiencing all the emotions that proper engagement brings. The advent of mobile phones brought a new dimension, and the focus shifted to recording the event rather than actually enjoying it. And now, in the age of me, me, me, the camera swivels round, and it's no longer about the event itself, but it's about being able to show your friends that you were there.

So for the Danish PM, the benefits were pretty clear. You may think we're a small country, known for our bacon, our detective series, our pastries and the Little Mermaid, but actually we are a big player on the world stage, and to prove it, here's me with my friends Barack and Dave. At least she was honest about it. Mr Cameron gave a pathetically self-serving reason. “When a member of the Kinnock family asked me for a photograph,” he said, “I thought it was only polite”. By invoking the name of one of the grandees of British politics - the Danish PM is married to Neil Kinnock's son - Mr Cameron was indulging in a transparently shabby, overly politicised piece of post-justification. It was way beneath him.

But a more important issue was the message that this entire, relatively insignificant, incident sent out. I have never entirely bought the idea that sports personalities or pop stars are “role models”, but it's a different question when it comes to the leader of the free world. I think we can reasonably expect Barack Obama to lead by example. At the memorial for a man who was once permitted to send and receive only one piece of correspondence, Messrs Obama and Cameron allowed themselves to become poster boys for a generation who find it impossible to live in the moment.