AGREEMENT across the divide on UK constitutional affairs is a rare thing, but could it be emerging on the issue of federalism? Earlier this month, the Constitution Reform Group of MPs said it was proposing a new Act of Union that would create a bottom-up federal system, and now the Scottish Nationalist MP Angus Brendan MacNeil has expressed some support for the idea.

Obviously Mr MacNeil is a nationalist and sees any new Act of Union as merely a pit-stop on the journey to independence, but his intervention in the debate comes after his colleague Pete Wishart also expressed his support for federalism during a debate in the Commons. It may be that they are simply showing their support because it makes no sense for a nationalist to oppose an extension of powers, but the CRG’s proposal also has great merit and points in the only logical direction of travel.

What the CRG is suggesting is that the four UK nations would “federate upwards” – in other words, they would each decide what is done at a national level rather than Westminster deciding for them. The theory is that such a structure would make the UK stronger and more appealing to many Scots and the group intends to put this idea to the test with opinion polls in the coming weeks.

It is a welcome development and, if there is emerging SNP support for it, that is welcome too. Ahead of the referendum in 2014, this newspaper argued that a more autonomous Scotland within a federal UK was the best way forward and it still has the potential to create a strong constitutional structure with less antagonistic relationships between the constituent parts.

There would be many problems to resolve, not least how we could create a federal structure that was not dominated by the largest nation. There would also be complex questions about how the finances of such a structure would work in the interests of all the nations. But the problems are worth tackling if the outcome is a more logical and more popular constitutional arrangement.