You read it here first:

“The party needs a fresh start from its new leader, and I think that is more likely to be achieved if I make a fresh start…  having thought it through, and discussed it with family and friends I am absolutely confident it is the right decision for Ed, for the party, and for me and my family. This is now Ed’s party to lead and he must be able to do so as free as possible from distraction…. This is because of the simple fact that Ed is my brother, who has just defeated me for the party leadership. I genuinely fear perpetual, distracting and destructive attempts to find division where none exists, and splits where they don’t exist, all to the detriment of the party.”

So all that stuff during the election campaign about him being “happy to serve” in Ed’s cabinet was a load of bananas…

UPDATE : The text is taken from a letter sent to his constituency chair. Guido was not subject to an embargo because he wasn’t officially given the text.