His success and reputation were legendary not only in Britain where his publisher had him flown about in a helicopter on poetry reading tours. By the 1980s he was regularly on call as visiting professor at Harvard University (1985-97) and at the same time professor of poetry at Oxford (1989-1994). The following year (1995), he received the Nobel Prize for literature.

Here at home, that award gave him a status unmatched by any other living writer, whether poet or novelist. It turned him into a national icon. He became Famous Seamus, a cross between a national treasure and a global guru. The twinkling eyes and the ever-smiling face, which somehow always remained inscrutable, gave him an aura of immense wisdom.

All this led many people, from presidents to plumbers, to his poetry. And that has to be a good thing. But fame is not the measure of how good a poet is and now, a year after his death, it is time for a more objective assessment. This is also made appropriate by the publication this week of his New Selected Poems 1988-2013, and the republication in a matching hardback of his earlier volume, New Selected Poems 1966-1987.

Together, the two volumes give us Heaney’s personal selection from his life’s work, the poems he regarded as his best. If these are the best poems he produced, then his reputation must stand or fall on them.

It is this reviewer’s opinion that it is high time for a new assessment of Heaney, not least because his work has also influenced Irish poetry. For better or worse, is the question. And there are many questions about the poet, the poetry and the reputation that need objective assessment.

Above all, Heaney was a poet of nostalgia for home and hearth, the turf-fire, the hen house and the bicycle. With the farmyard as subject matter, his poems are like exhibit notes in an agricultural museum. One of the results of this was to give his work an accessibility that compared well to Maeve Binchy, although her popular fiction was slightly more modern in content.

Another fundamental aspect of Heaney’s appeal was that although he was a poet from Northern Ireland who was writing during the Troubles, he managed to keep his distance from the sectarian horror, like most of his readers. Instead he adopted mythology and archaeology. He chose to write about ancient bog bodies rather than the more recent burials in Northern bogs of the bodies of victims of the “war”.

In “Exposure” he admitted having moved to Wicklow in 1972 and “escaped from the massacre” in the North. His preoccupation with pre-history and bogs distanced him from the sectarian war. “I found it more convincing to write about the bodies in the bog and the vision of Iron Age punishment”.

Heaney was always repressed and reticent about the North, as in “Summer 1969”. “While the Constabulary covered the mob / Firing into the Falls, I was suffering / Only the bullying sun of Madrid.” That poem concludes with his retreating for the “cool of the Prado” to look at Goya’s painting Shootings of the Third of May. This pretence to sympathy while on holiday, cooling off in exotic cities, was typical of his lazy political content. Thus a Heaney poem entitled “Thatcher” is not about politics.

As far as the writing itself is concerned, his poetic method isn’t great. He was fond of anecdotes chopped into lines. But is it poetry? His great flaw is “a nostalgia I didn’t know I suffered until I experienced its fulfilment”. He stated this in the introduction to the Anglo-Saxon epic Beowulf which is extracted among the New Selected Poems.

Heaney’s verse is swamped in nostalgia, like his titles: “Churning Day”; “The Forge”; “Gifts of Rain”; “Blackberry-Picking”; “Turkeys Observed”; “The Harrow-Pin”; “Conkers”; “The Seed Cutters”; “Nostalgia in the Afternoon”; “A Basket of Chestnuts”; “The Pitchfork”; “The Settle Bed”; “The Sandpit”; “Bog Oak”; “The Hill Farm”; “The Water Carrier”; “At a Potato Digging”; “The Gravel Walks”; “The Skylight”; “The Baler”; “Fireside” and “At the Wellhead”.

Solely because of the reputation of Heaney’s London publisher, Faber & Faber, many academics felt secure in praising him, like Harold Bloom of Harvard, John Carey of Oxford, and others such as Blake Morrison. They supported the American poet Robert Lowell’s misguided remark that Heaney was “the best Irish poet since Yeats.” Lowell’s backer was TS Eliot, the supreme modernist poet and founding-director of Faber & Faber.

After Eliot’s death, Charles Monteith from Lisburn, Co Down, took over the helm at Faber and reflected a taste in verse from his milieu as a former London barrister. Monteith’s mission at Faber in the 1960s aimed at sustaining their illustrious legacy of poets such as Lowell, Louis MacNeice, WH Auden, John Berryman, Ted Hughes and Sylvia Plath. Monteith decided to publish fellow Oxonian Richard Murphy and Heaney.

Monteith’s “finding” Heaney was good for business because the North was dominating the media. Heaney was decidedly a “safe” poet. Monteith rushed out four books over a decade. Heaney continually ploughed the same furrow in subsequent collections reflecting his folkloric submersion: Field Work, The Haw Lantern and Opened Ground. The Nobel Prize made him a brand name: Famous Seamus, coined by the TV critic Clive James.

To criticise Heaney’s poetry is not yet acceptable in academic circles. Those who have dared to, such as Desmond Fennell in “Whatever You Say, Say Nothing” (1991) and James Simmons in “The Trouble with Seamus” (1992), have been attacked, as though they were trying to kill a sacred cow. (Heaney, of course, wrote a poem in praise of bovine pregnancy, titled “Cow in Calf”.) The Heaney mafia fiercely protect his reputation. But despite his position as cultural icon, the fact is he never reached the achievements in literature of Wilde, Shaw, Yeats, Joyce and Beckett. His work is definitely not major.

An example of Heaney’s occasionally less than impressive ability with words is his best-known poem “Digging”, which compares a pen to a gun to a shovel. As usual his mealy-mouthed, heavy-handed metaphors are to the fore. It begins: “Between my finger and my thumb / The squat pen rests; snug as a gun”. This is simply inaccurate. A gun is not held between finger and thumb like a pen. A hand-gun is held properly using all fingers.

Heaney claims in the poem that his grandfather could cut more turf in a day “than any other man”. This is his standard trademark of anecdotes, frequently dull as ditchwater. “Digging” declares that he, Heaney, as a poet is unfit for farm work or turf cutting, having only his pen. He concludes: “I’ll dig with it.”

The poem is both simplistic and contrived. You write with a pen, shoot with a gun and dig with a spade. As someone born on a farm, he should have known the difference.

Posterity is no respecter of academies, honours, awards, reputations and one-time mass popular praise. These days, who reads Robert Southey, Alfred Austin, John Masefield, Cecil Day-Lewis, William Allingham and James Stephens? It’s quite simple: real poetry endures. Posterity decides.

Heaney’s first-ever published poem was entitled “Tractors”. His final collection Human Chain was set in his old familiar farmyard, saturated in mawkish descriptions amidst the usual wistful longings. The title poem is about lifting grain on to a trailer “with a grip on two sack corners”. Among his final pieces is “Banks of a Canal” which begins: “Say ‘canal’ and there’s that final vowel / Towing silence with it, slowing time.” These lines show him up as self-consciously drawing attention to language in melodramatic tones somewhat similar to Old Moore’s Almanac verse.

All this may seem harsh. But at this stage corrective views are essential if we are to begin to assess Heaney’s real worth as a poet. Some digging is required.