Today’s Guardian contains a contribution from a most unlikely source: Nigel Dodds, Parliamentary leader of the Democratic Unionist Party.

That this captain of Westminster’s most deeply small-c conservative party should take up his pen in Britain’s most self-consciously progressive newspaper is a surreal pairing that has a suitably surreal purpose: Dodds is riding to the defence of Nicola Sturgeon and the SNP.

This is, on the surface, rather unusual. Not least because of the radically different approaches that the two parties take on the vast majority of the spectrum of political issues both social and economic.

Indeed, less than two weeks ago Dodds was out and about in the Northern Irish press reassuring his unionist voters that the DUP would play no part in any parliamentary arrangement that let the Scottish Nationalists, grave threat to the future of the country that they are, into a position of power.

Yet despite those profound differences, the SNP and DUP have a lot more in common than the staunch unionists in the latter would care to admit, on the very issue which preoccupies both: the constitution.

Obviously the DUP are in favour of the Union and the SNP is not, but beneath that each of them operate similar constitutional strategies: hoarding power in a local legislature, de-legitimising and othering normal British politics, and treating Westminster as a money box.

It is thus not surprising that these two arch-regionalists have found common cause over Cameron’s plans for English legislation.

At the heart of Dodds’ piece is a fallacy that has previously been committed by other opponents of EVEL, such as Gordon Brown: that the Conservative proposals would create a two-tier Parliament.

What this argument ignores, whether deliberately or inadvertently, is that MPs have not been “fully equal to every other” since 1999.

There is, all too often, already a profoundly important and increasingly unjust distinction between members of the House of Commons: between those members whose constituents are actually subject to the laws it passes, and those whose are not.

The DUP Westminster leader is almost certainly right when he writes that: “I have yet to hear from a Tory colleague standing in England that a single door anywhere has been opened with the query, “whither Evel?””.

Yet if unionists are to learn anything from the deterioration of the Scottish situation since 1979, it is surely that the last thing to do is to wait until the constitution is being raised on every doorstep.

Northern Ireland itself is proof that once constitutional questions embed themselves at the heart of political debate it can be almost impossible to move on.

Dodds may also be correct to argue that EVEL is simply a continuation of the unfortunate unionist habit of lunging from one one-sided quick fix to the next, and that it will not address England’s real needs. But his article is totally silent on what the alternative is, and he must be aware that every proposed solution has serious downsides.

Thus despite its pan-British, pro-Union sentiments, we can place his article in a long tradition of MPs from devolved territories disinterring the best traditions of pre-devolutionary unionism to defend their privileged positions in the House of Commons.

These are most commonly heard from Labour MPs who, having voted time and again to pass power to their local devolved parliament, will make impassioned speeches about the virtues of “pan-British” participation in the formulation and passage of what is not, in truth, pan-British legislation.

As a unionist, I welcome the fact that one of Northern Ireland’s senior politicians may be in a position of national relevance, and feels the need to make his case in the national press.

Yet Dodds will have to accept that a diminution of Northern Irish influence at Westminster is a just and natural consequence of his party’s vociferous and pseudo-nationalistic opposition to ‘London rule’, just as his exclusion from the leaders’ debates stems from their deliberate maintenance of Ulster’s political isolation.

Reciprocity is the essential cement of the Union: if the DUP wanted a bigger role for Northern Ireland in British politics, they ought to have maintained a bigger role for British politics in Northern Ireland.