We now know for sure that Gordon Brown will have a virtual coronation as Labour leader. He will only be challenged by a candidate of the Left if they can muster the 44 votes required and there's no certainty that either Michael Meacher or John McDonnell can do that.

Mr Reid's decision not to stand is not a surprise - he has been considering his options over the past few weeks and he obviously did consider standing, but decided some time ago that was no appetite for a contest that he could not win. But his decision to leave the Cabinet has come as a shock.

It's almost certain that Mr Reid would have had the chance to carry on as Home Secretary under Gordon Brown and his decision, therefore, is a very big one - the end of his political ambitions. He has given up one of the big offices of state and his last act has been to reorganise that office, splitting off justice into a new department. And he's taken that decision after doing about eight or nine big jobs in the past ten years - and knowing that Gordon Brown wants to keep the same team up to the general election.

A friend who spoke to John Reid this morning said that he was "knackered" and looking for a break. He remarried a few years ago and he genuinely wants to spend more time with his wife and she with him - as well as on other passions such as supporting Celtic. So now feels like a good time to go to the new leader peace.

He may not have been Mr Brown's biggest admirer but he has said that he will back him and by going he believes that he can remove one element of tension from the scene. I believe that he has told friends that because he has always been seen as confrontational - he has removed a possible source of trouble. I do not think he has taken any decision yet on whether to leave parliament.

We know that Mr Brown wants to bring loads of new ministers from the middle ranks into top jobs and this gives him one more slot. I would expect Brownites such as Ed Balls, Ed Miliband and Yvette Cooper to enter the Cabinet. I also expect James Purnell and Andy Burnham to join them and there could be a recall for John Denham and even for Charles Clarke, who told The Times last week that he would serve Mr Brown if asked.

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