Today’s story that Jim Murphy plans to make Scots an open-ended offer of NHS spending explicitly funded by the South East of England is depressing on several levels.

For a start it is, as Guido points out, a really moronic thing to promise. By couching their offer in the terms of “SNP plus X”, they have completely ceded the political initiative to their opponents. The Nationalists are now free to promise a number of nurses at the very top of the range of just-about credible and force Labour to over-bid.

This poses no small challenge to Labour’s efforts, reported elsewhere in today’s newslinks, to shore up their economic credibility. It’s little good having Ed Balls dolefully telling the London press about all the cuts and spending restraint Labour would enact in office if the captain of their northern flank is pinning them to open-ended spending commitments.

And that northern flank is getting more press attention than it might have in the past. Not only has the referendum campaign heightened press interest in the devolved territories, especially Scotland, but Murphy is very much London’s golden boy.

To pick just one example, the Sun crowned the Scottish Labour leader their political “Hero of the Year” (£). After praising him for offering “voters an alternative to Ed Miliband’s left wing, intellectual leadership” and for being “prepared to fight for his beliefs, passionately and successfully” the paper finishes with the following plea: “Don’t stay up there too long Jim, your wider country may need you.”

Whilst obviously pleased that he saw off mystifying throwback Neil Findlay, what are Murphy’s London supporters to make of his behaviour since being elected? After all, reckless spending pledges and anti-London grandstanding were very much part and parcel of Findlay’s offer.

If this nurses pledge is any indication, Murphy has decided that shoring up Labour’s position vis-à-vis the SNP with its left-wing Scottish voters is more important than challenging the complacent misconceptions at the heart of Scottish politics in general and Scottish Labour in particular. Murphy the aggressive street fighter is in evidence; Murphy the Blairite reformer is not.

It also suggests a rather bleak attitude towards the Union. Using a British tax to fund a Scottish giveaway – which the SNP can’t do because “there are too few mansions in Scotland” – is about as mercenary a method for demonstrating the advantages of the UK as can be imagined.

It must be particularly galling for those who hoped Murphy would use the fact that there aren’t many mansions in Scotland to challenge the status quo and advocate wealth-creating policies, rather than justify a traditional giveaway.

Another impact of the referendum has been to raise the prominence of constitutional issues, and it is here that the most potent problems posed by Murphy’s nurse stunt lie.

First the mansion tax will be set by London, not Edinburgh. Labour have not yet revealed all the details of their proposals, but are we to believe that the Shadow Chancellor will commit to setting the mansion tax – which falls almost exclusively on English ratepayers – at a rate which suits spending commitments made unilaterally in Scotland? It would be a political gift to the Conservatives of the highest order.

Second, one of the key justifications for the latest tranche of powers being passed to Holyrood was that making the Scottish Parliament responsible for raising its own funds would lead to some fiscal responsibility north of the border. That isn’t going to work if Scottish Labour use the Barnett Formula to continue tapping into the bank of Britain to outspend the Nationalists at England’s expense.

With his “vote for me to screw money out of England” message, Murphy is setting some dangerous and deeply counter-productive political precedents.