Let's see if I can get my head around this:
Before the referendum, with the Yes campaign showing a slight lead, Gordon Brown blitzes into Scotland and presents a pledge that if Scotland votes No the three main Westminster parties will grant Scotland significant extra powers – "a modern version of home rule", as Brown puts it (whatever that might mean).
Cameron says that he is happy with the vow made by Brown. The Labour party back his promises. The front page of the Daily Record is taken up with a vow by all three party leaders to stick to the promises made. Better Together official campaign literature details a schedule of events which will happen after the referendum to deliver these powers, starting with the presentation of a motion to Parliament on the 19th of September in the event of a No vote.
Many commentators argue that Brown has no power to offer anything, that nothing he promises can be delivered, that any promises he makes can be ignored after a No vote, that the three main parties do not even agree with each other on powers to be devolved. Andrew Neil tries to pin down politicians from both Labour and the Conservative parties on what powers might be, and despite grilling them for over five minutes, gets precisely zero information. 
Other commentators pull apart the alleged powers on offer, showing how they are neither new, nor of any use,  and, indeed, how they can be used to punish Scotland. 
And now, quelle surprise, after everything has started falling apart  here he is, trying to bandwagon himself to a petition calling on the Westminster parties to actually deliver what they promised.
"Mr Brown wrote: "The vow made by three party leaders on September 16 was a self-standing set of promises to the people of Scotland."
"Yet immediately after the referendum result, a new proposal that was never raised in the pre referendum discussions and yet being material to the referendum should have been raised before the vote was introduced – to lower the status of Scottish MPs in the UK when voting on matters including tax."
That's your fault Mr Brown. You made it clear you had the backing of the three main party leaders. You implied that they had agreed to the timetable you promised Scottish voters would happen. You went around Scotland spouting their lines in order to get Scotland to stay in the Union – when you weren't spouting utter rubbish about transplants  and pensions  in an independent Scotland. Now you have to live with the results.
There is no point in pretending you have been wronged. You are an experienced politician, and if you didn't check that all the parties were actually on board, and that they all had the same plans, then that's because you chose not to do so. And I think we now can all see why you chose not to do so. This surely has to be the end of your political career in Scotland.
Mr Brown has also outlined a ’14-point practical plan for new powers’, which include more control over investment, job creation and taxation.