With no hint of majesty, and the merest suspicion of irony, poet Michael Longley describes himself as “Britannic”. For a man born to English parents in Belfast at the outbreak of the Second World War, then raised in Northern Ireland and, finally, remaining resident in Ulster throughout the Troubles, “Britannic” is the mot juste. And so, he concludes, looking back on his early life from the eminence of his 68th year: ‘I was brought up in a house with English voices and I had to go out and find my way.’

He’s been doing that all his life, with an innate English diffidence that is not insecurity so much as a loathing for ‘side’. In this, as in so much else, Longley’s Roman, rumpled, chunky demeanour evokes a schoolmaster of that bygone age. ‘You take your poems seriously,’ he instructs, ‘but you don’t take yourself seriously. What the muse hates more than anything is self-importance. Shakespeare wasn’t self-important, was he?’

As a young man, studying at the Royal Belfast Academical Institution, he was ‘an aesthete in private, a hearty in public’ who says he was slow to commit to print. Actually, with his lifelong friend, fellow poet Derek Mahon, he now seems rather precocious. By the time he graduated from Trinity College Dublin, where he had steeped himself in the classics, he was definitely on his way - at least until he returned to Belfast.

‘The point of growth in a young artist’s life,’ he says now, ‘is when he feels hurt.’ Longley had been cheerfully competitive with Mahon at TCD. In the Belfast of the early 1960s, there was a creative ferment centred around poet Philip Hobsbaum in what has become mythologised as the Group. No one would have paid much attention to this provincial poetry circle but for one thing: the occasional presence at its revels, in 1963-64, of a gifted young farmer’s son from County Derry named Seamus Heaney.

Longley is at pains to insist that he and Heaney are friends but, not far across the easy surface of his recollections, we soon scrape against submerged reefs of competitiveness. When he speaks of himself as a young poet, Longley remembers ‘some kind of wan paleface beside Seamus and his frogspawn’. A few moments later, he mentions the ‘pang of jealousy if somebody got a poem in the TLS’.

Longley was now in a real competition to scramble to the top of Parnassus. ‘We were like splinters,’ he says, ‘keeping an eye on each other.’ When Heaney got a publishing contract with Faber, ‘I was jealous, yes, but delighted, too’. He goes on: ‘Seamus is probably the only poet in the history of the world who had a poem published in the same week in the Listener, the New Statesman and the TLS. I mean, he’s gifted, but unbelievably lucky.’ He corrects himself, reflectively: ‘My feelings were not so much of jealousy as a fear of being left behind.’

Next to the leaping fame of Heaney, Longley is perhaps the tortoise, slowly accumulating lyric miles - Gorse Fires (1991), The Ghost Orchid (1995), The Weather in Japan (2000), Snow Water (2004). Today, on the publication of his Collected Poems (Cape £25), he looks like a winner. The new volume represents 40-something years of work and includes everything he has written, with just 10 omissions. In that schoolmasterly way he has, he says: ‘I felt I had to be true to the earlier selves.’

Those earlier selves encompass a remarkable career as a practising poet during the bloody span of the Troubles. For much of his career, until he quit in his early fifties, he was a director - ‘somewhere about the colonel class’ - in the Northern Ireland Arts Council, a beacon of sanity as the bombs went off and the troop carriers rolled in. From time to time, he and his wife, Edna, wondered about leaving, but in the end they stuck it out.

Longley insists, rebutting the cliché about war and poetry, that the Troubles have nothing to do with his creativity, except in the negative sense that for some years he wrote nothing: ‘All the time, there was this black cloud hanging overhead.’ He is modest about his considerable contribution to the creative healing that had to be done in the aftermath of fratricidal violence and couches it in classical terms. One of his finest poems, “Ceasefire”, written after the first IRA ceasefire, takes its inspiration from The Iliad. Possibly the poets ‘stopped things getting worse,’ he thinks, ‘and what you can do is remember the dead’. Another of his most celebrated acts of remembrance, “The Ice-Cream Man”, is a lovely elegy for a murdered shopkeeper: ‘I got a letter from his mother thanking me for the poem. I treasure that letter. It’s worth all the good reviews put together.’

Hoping Collected Poems is ‘a milestone, not a tombstone’, Longley continues to compose. ‘The most important poem is the next one. Perhaps I’m still finding my voice,’ he wonders aloud. ‘I don’t write art about a deeply insisted-upon cultural sense of myself.’ Perhaps not. A remarkable number of the poems here display a classical inspiration and are often versions of Horace, Ovid or Catullus. ‘I hope by the time I die,’ he says, ‘my work will look like four really long poems. A very long love poem; a very long meditation on war and death; a very long nature poem and a playful poem on the art of poetry.’

So, at the end of the day, a phrase beloved of Ulster people, Longley does have an identity that sings through almost every line he writes and it is “Britannic’. Still, he says he would ‘hate to be called anything but an Irishman’, but in the next breath asks: ‘How can I deny my father’s gentleness and his lovely English lack of emphasis? I come from a place where the finger is wagged and everyone’s over-certain. Plus, I’m an Anglophile.’

He tells a story about driving with Heaney to a protest march after Bloody Sunday. ‘It was a time when things were very tense and cars were being stopped at gunpoint. I said to Heaney, ‘If we’re stopped, what do we say?’ We decided that, at the point of a gun, I was a Protestant and he was a Catholic. We’d simply swim by what we were.’

Longley is probably most comfortable swimming in English water. He celebrates the great English poets - Hardy, Owen, Sassoon, Rosenberg, Larkin, Hughes. ‘I don’t think the English quite appreciate their own native line,’ he says, adding that he feels part of it. As our conversation draws to a close, he remarks he has been meaning to learn Irish Gaelic for ‘about the last 30 years. I got myself a teach yourself book’. He laughs. ‘I can’t even get beyond the pronunciation in chapter one ... I’m deeply jealous of those people who pick it up as a matter of course, as children.’