Today brought yet another twist in the saga of the 'Wendy Commission', the devolution plan put forward by Labour's Holyrood leader in opposition to the Scottish Government's National Conversation.
Backing her plans for a fresh study of devolution, Mr Brown said: "There is an issue about the financial responsibility of an executive or an administration that has £30bn to spend but doesn't have any responsibility for raising [that].
"In any other devolved administration in the world, there is usually a financial responsibility that requires not only the spending of money by the administration but also its responsibility to take seriously how it raises money." (BBC News)
However, his suggestion that Westminster could take some powers back from Holyrood will only increase concerns that Alexander's proposed constitutional commission is being downgraded into a review under tight control from Westminster.
It is currently being suggested that the appointment of Menzies Campbell as chairman might boost the commission's credibility.
The Lib Dems will want to ensure that Campbell is not exploited by Brown as he was when he was Lib Dem leader. That requires a commission with a strong remit that can deliver their policy of devolving tax powers to Holyrood.
Brian Taylor, interviewed Gordon Brown for the Politics Show, questions that possibility on his blog:
The snags? You might choose to assign VAT or corporation tax. But European Union rules almost certainly preclude a devolved Scotland from varying the rate of those taxes. Which rather defeats the purpose of allowing fiscal discretion. (Blether With Brian)
That snag may already have been removed by the review of taxation in Northern Ireland, which Brown commissioned from Sir David Varney. As I noted at the time over at OurKingdom, the report concluded that EU law was not an obstacle to fiscal devolution:
A move to a differential corporation tax rate for Northern Ireland would be possible in principle. However, it would involve legislative changes and legal issues would affect the design of such a scheme. Also, the fiscal consequences of such a move would have to be borne immediately by the Northern Ireland Assembly. Varney Report
Varney nevertheless came out against any significant changes to Northern Ireland taxation for other reasons. Given Scotland's greater significance in British politics, and the raised expectations there, the Scots are in a much better position to extract concessions which may ultimately have to be extended to the other side of the North Channel as well.