Look back, this St George's Day, to 1999, when Scots and Welsh voters first elected their new devolved governments. The convergence between the results was striking. In Scotland in 1999, Labour came top of the constituency poll with 39%, with the SNP nationalists second on 29%, the Conservatives 16% and the Liberal Democrats 14%. In Wales that year, the constituency result was Labour 38%, Plaid Cymru nationalists 28%, Conservatives 16% and the Lib Dems 14%. To all intents and purposes, Scotland and Wales seemed in political step, albeit with different devolved powers. In both, although only after trying to govern alone in the Welsh case, Labour eventually took power with Liberal Democrat coalition support.

Now fast forward 12 years to the latest opinion polls in the two countries for their latest devolved elections, the fourth in both cases, which are due to be held on 5 May. The striking thing today is how Scotland and Wales are no longer in step and now appear to be marching to very different drums. In Scotland this week an Ipsos Mori poll put Labour on 34%, SNP 45%, Tories 10% and Lib Dems 9%. In Wales, by contrast, on YouGov's most recent poll there, Labour is on 49%, Plaid Cymru 17%, Tories 20% and Lib Dems 8%. An opinion poll is only an opinion poll, and is certainly not an election result, but it seems increasingly possible that, while Wales is swinging heavily behind Labour in the face of the Tory-Lib Dem coalition in London, Scotland may re-elect the SNP administration that first took power there four years ago.

Results like these would certainly be a blow for the London coalition parties, though hardly an unexpected one. The Lib Dems are facing a particularly brutal outcome, with the prospect of steep losses in places that have been Liberal for generations. The picture is more mixed for the Tories, who retain a stronger position in Wales than in Scotland. Yet there is some solace for the UK coalition too. These are the first devolved elections to take place with Labour, the original begetter of devolution, no longer in power at Westminster. After a torrid first year for the London government, Labour might have expected that the voters would place the party firmly in its traditional place at the head of the Welsh and Scottish opposition. A few months ago this still looked likely. Now, an important lesson, it is much less certain. Reasonably enough, voters in both countries seem to be thinking at least as much about the politics of Wales and Scotland as about the UK. In Wales that benefits Labour rather than the nationalists. In Scotland the effect increasingly looks to be the reverse. But that's the logic of devolution. The union may survive. But the old ties no longer bind as tightly as before.