Everyone is jumping on the bandwagon and saying they guessed long ago that Ed Miliband would be the next Labour leader, including Iain Dale and Guardian writer Jenni Russell, to name but a couple.

But I believe he set his heart on it much longer than most people realised, and that his simmering ambition had been spotted by those close around him as long as three years ago.

I met the ace PR blogger  Stuart Bruce , a keen Labour supporter, at a social media event in London in April 2007 and we talked about David Miliband’s blog which he was writing as Environment Secretary. He had been advising him on this and told me he had personally recommended my blog as one for David to include on his website, and my link sat there along with Sky’s Adam Boulton and the BBC’s Nick Robinson, as well as other leading UK bloggers. I did feel privileged, despite our political differences.

We then talked about whether David would become the next Labour leader and Stuart said no, that the one to watch out for was Ed Miliband. He was aware then that either Ed wanted to pursue the Labour leadership, or others had spotted his potential, including Stuart.

As a very driven and politically hungry younger brother, he must have felt marginalised and in the shadow of David who later became Foreign Secretary. But just like Tony Blair failed to deal with Gordon Brown, so did David when he ducked the chance to challenge his leadership at a time when his party and the country felt increasingly disenchanted with him. He failed to seize the moment.

I suspect it is one regret he will live with for the rest of his life, but I hope he doesn’t let it turn into bitterness.  He had a standing ovation today for praising Ed. As we know, it’s harder to be a lose than a winner. I can’t say whether David feels able to serve in Ed’s Shadow Cabinet, the personal hurt might be too great.

At the end of the day Ed’s fierce determination to win superceded brotherly love and loyalty. But that’s what makes politics so gripping.