The poet himself was in no doubt, famously scolding the editors of the 1982 Penguin Book of Contemporary British Poetry: "Don't be surprised if I demur, for be advised/My passport's green./No glass of ours was ever raised/To toast the Queen".
(This, if memory serves me, occasioned an instant riposte from another well-known Irish poet, along the lines of: "Good on you, Seamus,/Knocking the Brits who made you famous".)
I mention this because in the Christmas issue of the Times Literary Supplement, backpage columnist JC seeks to reappropriate Heaney as an Englishman abroad.
"They won't thank you for saying so south of the six counties," JC writes, "but there is a sense in which Seamus Heaney was our national poet".
Pointing out that the Nobel laureate was "born and educated in the United Kingdom", JC further claims that he was "admired, even loved, by readers throughout Britain more than any latter-day poet we can think of".
Arguing that "neither Gunn nor Hughes comes close", he maintains that Larkin "had no popularity beyond his books", whereas Heaney had "deep public appeal" in "abundance". Indeed, "one could say of him that it came naturally to him to be liked".
Few would argue with that, and indeed if Britain wants to embrace him as its national poet, so be it, just so long as those of us who live "south of the six counties" can do likewise, while also claiming national ownership of such other honest Ulstermen as Louis MacNeice, Michael Longley and Derek Mahon.
It's all a vexed question, I suppose. Indeed, it's worth bearing in mind that in their 1958 Oxford Book of Irish Verse, editors Donagh MacDonagh and Lennox Robinson included six poems by Robert Graves, that Wimbledon-born and most quintessentially English of poets.