The Complete Poems by Philip Larkin, edited by Archie Burnett

What is a poet's "real" work? Is it the best, canonical poems – the writing he or she is known for? Or is the poet "really" located somewhere else, among the false starts and revisions, both personal and writerly, that produced this canon?

Literary biography is once again highly regarded. Today's heirs to Lytton Strachey and even Max Beerbohm – figures like Michael Holroyd or Claire Tomalin – are among our most distinguished writers. Perhaps their very seriousness encourages us to believe that the truths to be found beyond the printed page aren't merely human but also literary.

Certainly, a desire to explore work that poets have chosen not to publish seems to be an emerging trend. Recent attention has focused on the notoriously perfectionist Elizabeth Bishop. Her juvenilia, rejected drafts, letters and paintings have all been brought into the public domain. Hugely enlarging access to the material, this is marvellous for fans. Yet we can't ignore how difficult this shy writer would surely have found the intrusion; or how it undermines her famous, years-long agonising over individual lines.

Now it's Philip Larkin's turn. The Complete Poems, a handsome 700-plus pages of scholarship and material both familiar and unseen, is edited by Archie Burnett. Conspicuously, the four collections Larkin published in his lifetime – The North Ship, The Less Deceived, The Whitsun Weddings, High Windows – occupy fewer than a hundred of these pages. Depending on your point of view, this is either proof of the book's necessity or its hostage to fortune.

What is undeniable is that, now that the volume exists, it is a must-have for anyone who enjoys Larkin; or indeed for anyone much interested in poetry at all. For, as the 20th century recedes, Larkin seems more and more to be the writer today's British verse has to come to terms with.

He may not have been the greatest poet of the last century. But Larkin exemplifies the problems and successes of a particular British – perhaps we should even say English – poetics. Modernist or not, those giants TS Eliot and WH Auden – or Ezra Pound and Louis MacNeice – never gave themselves fully to a cultural Britishness. Their writing deploys a wider set of influences. By contrast, Larkin seems to have set himself the task of getting a peculiarly national sensibility into verse. Though a career in university libraries might seem pretty much an ivory tower, the poems by which he is best known share a great deal of their outlook with the man on the Number 53 bus.

Famously compromised by "hatred of abroad", Larkin's imagination is nuanced by piano stools, souvenir saucers, graffiti and other impedimenta of post-war Britain. Grumbling, and mistrustful of big ideas, it nevertheless seems able to conceive of grace when that is made concretely manifest: "If I were called in/ to construct a religion/ I should make use of water." It is capable of a limited compassion – "Something is pushing them/ To the side of their own lives"; "Man hands on misery to man" – though one often directed towards the speaker's self. Or perhaps, in being compassionate to everyone, the poet is also compassionate to himself as everyman. After all, "All streets in time are visited" by "Ambulances".

But Larkin can't be reduced to a provincial curmudgeon in funny specs. What makes him intractably important for British verse is the supple accommodation he achieves between things quotidian and epiphanic. The poet who emerges in 1955 in The Less Deceived is able to move between the demotic and the frankly transcendent without scaring the horses; or our man on the Number 53. No other 20th-century poet manages quite this trick of continuity between experience, emotion and metaphysics.

In poem after poem, it is as if the Larkin-narrator voices-over a panning shot round circumstance, then turns to explicate direct to the camera, which has alighted on him: from the "It is intensely sad" of "Money", to "Let it always be there" of the annual "Show Saturday". Another poet would change gear audibly into the lyric lift-off characteristic of The Whitsun Weddings and High Windows, but Larkin segues into the redemptive with some of his most memorable lines: "Somewhere becoming rain", "What remains of us is love". These fit the collective British palm so snugly perhaps just because they use plain speech, and understatement.

Of course, as all this reminds us, Larkin was one of the great post-war modernisers. But that he hasn't dated – as a poet, however antediluvian his sexual politics – demonstrates that he was apt for more than a zeitgeist. Now, with The Complete Poems, we have the fullest background to date for that carefully constructed poetics.

Archie Burnett is distinguished for his scholarly editions of AE Housman: another poet who used a human line and scale to explore his own version of Englishness. Here, Burnett's notes offer a fascinating, compendious vade mecum into Larkin's poetic world. Full of reassuring exactitude about variants, and extensive reference to the poet's own comments on the work, they are most stimulating of all when they cite buried sources, such as Eliot's use of the odd verb "construction" in the context of religion-founding.

These notes are at the heart of a fluently-organised volume. The four collections are followed by other poems published in the poet's lifetime, poems unpublished but dated, and other unpublished poems. One appendix features Larkin's first attempts at collections, another dates all the poems by year. A lot of thought as well as an enormous amount of research has clearly gone into this arrangement. In 1988, Anthony Thwaite's first edition of the Collected Poems broke apart the poet's artistic intentions by interleaving work both collected and uncollected in order of composition. This was generally agreed to be too great an intrusion of literary scholarship on the poetry itself: in principle not dissimilar to breaking apart actual poems and inserting drafts.

Happily, Thwaite's 2003 edition restored the integrity of the four collections, while offering a substantial side-order of uncollected and unpublished verse. There remained, though, some questions about what had been excluded, and why. Last year, Martin Amis edited Selected Poems. Though one might wonder whether a poet so scrupulously self-pruning as Larkin needs further winnowing, Amis established the intelligent precedent of shifting the Larkin canon largely away from The North Ship (from which he reprinted only one short lyric) and including six uncollected poems. Offering a writerly, readerly response to the question of why Larkin matters, Amis's answer is, in effect, "Because he's good: and these poems prove it".

Burnett's project might be summed up, more simply, as: "You can't have too much of a good thing". But that depends, of course, on what a good thing is. The most determined scholar surely couldn't believe that Larkin wanted his work viewed through the lens of jingles such as this to Kingsley Amis in 1977: "Well, I must arise and go now, and go to Innisfree,/ Where I have heard it rumoured you can get Guinness for free". Even the scansion of this annoys.

Gossipy, often furious, frequently obscene, Larkin's use of rhyme in letters to pals is part of that clubbable, not tremendously politically-correct, limerick-obsessed and punning culture that we all know forms part of a certain kind of masculine literary friendship. Not being unusual, it seems unfair to judge Larkin in particular by it. Unfortunately, his isolation means that what could have remained pub gossip, treated as no more than biographical ephemera, was recorded for posterity in his correspondence.

This isn't an argument against publication; but it does suggest that it might be more accurate to publish some of these pieces in and as the letters they undeniably are, rather than collect them as poems. When the playground snigger of rhymes like "Barbara Pym/ quim" and "Whitman/ not a titman" irritates, that isn't (only) because of the objection Larkin anticipated, in a letter to Robert Conquest: "'Oh, how beastly'". It's because the public, published Larkin took serious care over his work, and this literary care is being overruled.

Not all the uncollected verse falls into this category. The famous, and consummate, "Aubade" postdates Larkin's final collection. Draft poems like "Holiday", from the 1960s, throw fascinating light on the three volumes of his maturity. The question of where to draw the line remains a tricky one: Thwaite's first Collected placed The North Ship among the juvenilia.

And it's not simply a question of portraying Philip Larkin in a good light. Burnett isn't a torch-bearer but a scholar: brilliant, forensic and independent. It might, though, be a question of category error.

Like dogs nesting in old blankets, writers routinely preserve unpublished drafts and jottings; archives collect such methodological evidence. This indicates no writerly intention that they should form part of the published oeuvre. To be exhaustive, as Burnett brilliantly is, is not necessarily the same as to be comprehensive. This book does indeed give us substantially more of Larkin. But the true gain is in Burnett's own precise, insightful exegesis.

Fiona Sampson's 'Percy Bysshe Shelley' (Faber) and 'Music Lessons' (Bloodaxe) appeared in 2011