So, what are you doing with your retirement? It’s a question I’m often asked, and at some point in my answer I have to own up to the fact that I’m writing a book (‘Neither am I,’ Peter Cook would always say at this juncture – but I am, really). It then becomes tricky, because the book is rather hard to describe, at least in terms that aren’t going to lead to an awkward silence and a swift change of subject. The fact is that the theme of my book (now nearing completion) is English church monuments. Worse, English church monuments of a particular period, roughly speaking the 17th century. I don’t think there’ll be a scramble for the film rights.

But hear me out. Those monuments I’m writing about represent a wealth of superb, world-class sculpture, here in England – and almost nobody even knows it’s there. Why? Largely, I guess, because so many of these wondrous monuments stand in obscure parish churches, scattered across the country, often in remote locations. One of the greatest of them, for example, Epiphanius Evesham’s hauntingly beautiful monument to Sir Adrian Scrope, stands in the isolated, little-visited church of St Leonard’s, South Cockerington, in an all but deserted corner of Lincolnshire. If a gallery full of these monuments were to be assembled in a national museum, their beauties would be obvious to all – but, as it is, they must be sought out, and that isn’t always easy. It involves a good deal of research and much travelling to out of the way corners of the country. And then there is the frustrating problem of getting inside.

So often on my travels I’ve come across church doors firmly locked. I know now to telephone beforehand, make the necessary arrangements and hope for the best. Even the redoubtable Mrs Esdaile, author of the essential English Church Monuments, 1510–1840 (1946), sometimes encountered a locked church. It happened once when she was visiting Stowe Nine Churches in Northamptonshire to see the monument to Lady Elizabeth Carey, a marvel of white marble carved by the great Nicholas Stone. Remonstrating with the rector, she was duly chastened when he told her he had recently surprised a pair of Americans trying to prise up Lady Carey’s effigy with a crowbar. There are sometimes good reasons for keeping a church locked.

Existing books on church monuments, with the exception of Mrs Esdaile’s (and especially its long introductory chapter by Sacheverell Sitwell), tend to be dry, antiquarian accounts, more like catalogues than books that anyone would want to read. The sheer aesthetic charge that the best monuments deliver is barely even hinted at in these resolutely objective works, whereas it will be central to mine, which might almost be called (but happily isn’t) ‘The Joy of Monuments’. But it isn’t only about monuments; it’s as much about people and places, mortality and immortality, poetry and butterflies.

It’s not a scholarly treatise, or a heritage guidebook, or a gazetteer – but nor is it the sort of book a publisher would want to be made of this subject: a ‘journey of discovery’ with a catchy title, each chapter beginning with a bit of first-person scene-setting (‘It’s a wet Wednesday and I’m standing in the middle of nowhere – or, to be precise, South Cockerington, where I have an appointment with Sir Adrian Scrope’). That’s exactly the book I didn’t want to write. What will come out (before the end of the year) is the book I wanted to write. This means I shall be self-publishing, and that, no doubt, is going to be an adventure in itself – a ‘journey of discovery’, even.

Philip Larkin is a persistent presence in my book. It was an encounter with a church monument, in Chichester Cathedral in the winter of 1956, that inspired one of his most famous poems, ‘An Arundel Tomb’. The monument, battered and not especially distinguished, is a 14th-century work commemorating Richard FitzAlan, tenth Earl of Arundel, and his second wife, Eleanor of Lancaster (their actual tomb is at Lewes Priory). Their hands are joined together, and Larkin, having never seen this on a monument before, found the detail ‘deeply affecting’. However, he later had reservations about ‘An Arundel Tomb’ as a poem, because he’d muddled up the hands (the earl’s right hand, not his left one, holds the countess’s own right hand) and hadn’t realised that the effigies were restored in 1843, at which point the joined hands currently on the tomb were carved (the originals having been lost). He might have learned, too, that the gesture of joining hands is not uncommon on medieval monuments and connotes something much closer to dynastic union than to romantic love.

Larkin is now remembered more for the resonant last line of that poem – ‘What will survive of us is love’ – and the equally resonant first line of ‘This Be the Verse’ (‘They fuck you up, your mum and dad’) than for anything else he wrote. ‘What will survive of us is love’ is far from a heartfelt statement, still less an assertion. It’s almost strangled by reservations: ‘Time has transfigured them into/Untruth,’ writes Larkin of the hand-holding effigies. ‘The stone fidelity/They hardly meant has come to be/Their final blazon, and to prove/Our almost-instinct almost true:/What will survive of us is love.’ What has survived most tenaciously of the poem is that last line, wrenched out of context to become a favourite consoling quotation, often read at funerals. The Arundel monument has become one of the most famous and most visited in England. And Larkin’s stone in Poets’ Corner, in Westminster Abbey, is inscribed with those last words he hardly meant.

When I began the book, I thought I’d be ending it with those words – which would have been nicely symmetrical, as I begin it with Larkin and his other great church poem, ‘Church Going’. There is no better evocation of the feeling that comes with stepping for the first time into an unfamiliar church, into that ‘tense, musty, unignorable silence,/Brewed God knows how long’ – a mix of abashed self-consciousness, awkward reverence, bewilderment and awe. I still feel it every time. And what words will end my book, if not Larkin’s? I think I know, but I haven’t written that last chapter yet. Time to get on.