This is a remarkable book. Larkin was an assiduous letter writer throughout his life, and this book presents over 40 years of them, to a very broad range of recipients, many well-known (Kingsley Amis, Douglas Dunn, John Wain, John Betjeman). Letter-writing featured strongly in both Larkin's completed novels, and can be seen to be a very important aspect of his life. But as both "Jill" and "A Girl In Winter" suggest, letter-writing not only acts to entertain and send news and gossip to the recipient, but also offer a partial self-definition. You write TO a particular person, and what you write is in part defined by that person. This is particularly the case here, where Larkin's voice and register change dramatically not only over time (as you'd expect) but very much by the recipient.
So, to start with, Larkin's youthful letters are a delight, as he is keen to impress others with his intelligence and his profound discoveries of the world around him. With JB Sutton, he becomes intimate as with no other, and reveals his profoundest worries, amidst much DH Lawrence worship, but gets stuck in this vein. With Kingsley Amis he is matey, blokish and hard-swearing. With Robert Conquest later on, even more so (with additional pornographic interest). The main biographical interest in this book will be, I suppose, his letters to the women in his life. To Monica, his main lover and companion (and his intellectual equal), he is profound, honest and self-castigating, whereas with Maeve (his "love") he is far more generous, tender and much less self-concerned. Things start to alter in the 1960s, though, as he starts to sour, and his letters to Amis and a former school friend Colin Gunner become almost staggering outpourings of vitriolic bile. They are always funny, suggesting that he isn't entirely serious, but because the attitudes are elsewhere expressed far less intently, you realise that he did hold those opinions. (There is a recording somewhere, of Larkin drunkenly singing a racist ditty that is quite stomach-turning). The closing few years are grim to read.
Nonetheless, it must be said that this is an absolutely fascinating volume to read, massively enlightening about Larkin's poetry, featuring pleasing amounts of literary gossip, portraits of many literary figures and many opinions and attitudes which broaden our knowledge of Larkin the man. To be read by any fan of Larkin's poetry.