John Piper, Myfanwy Piper: lives in art, By Frances Spalding

A double act in word and image

Frances Spalding has a superb track-record as a writer on British art. She is an archaeologist of lives: a delver and unearther par excellence.

At her scintillating best, she is both a brilliant encapsulator and shrewd summer-up; above all, an enthusiast and advocate whose wisdom makes you eager for her subject. Superbly illustrated with colour plates, photographs and generous line drawings, this is a bumper book on both artistic Pipers, John, the painter, illustrator, stage designer and war artist; Myfanwy the opera librettist and critic. Apart from a fine chapter in Jerrold Northrop Moore's The Green Fuse, Spalding's is the most significant contribution to Piperology since Richard Ingrams's Piper's Places and Orde Levinson's John Piper: A catalogue raisonné.

Like Iris Murdoch and John Bayley, the Pipers were a barometer of an age that has all too nearly passed us by. Together, the duo spanned almost a full century. John was born in 1903; Myfanwy died in 1997 at Fawley Bottom, the flint-and-brick Chiltern farmhouse which they found, by a curious osmosis, near Henley-on-Thames. Then run-down, it was soon to be riddled with book-rooms and crannies, a kind of antiquarian bookseller's paradise. Having tamed (though not too much) Fawley and its sinuous valley, they started a family: two girls and two boys added a mélange of scampering feet and laughter to John's sprawling outhouses (soon piled high with maquettes for the rebuilt Coventry Cathedral) and Myfanwy's ramshackle kitchen, where seasoned aromas wafted, apt red wines lurked and the ghosts of WH Auden and a gangly, twentysomething Benjamin Britten perhaps still walk.

Britten belonged to both John (initially) and Myfanwy, yet she made him her own. It was John Betjeman's bicycling "my Myfanwy" ("Soap-scented fingers I long to caress"), dreaming spires-educated Myfanwy Evans, for whom Piper, almost 30, fell. They married in 1937. She was still a chrysalis of 23. Myfanwy replaced artist Eileen Holding, John's first wife, with whom he confided he was sexually incompatible.

Myfanwy was the very opposite. The budding intellectual chrysalis burgeoned into a fully-fledged butterfly. Encouraged by French abstract artist Jean Hélion, Myfanwy founded her own short-lived, cutting-edge, astonishingly influential art magazine, Axis. While John designed sets, Myfanwy wrote not just her three libretti for Britten (The Turn of the Screw, Death in Venice and Owen Wingrave), but for Welsh composer Alun Hoddinott and Australian-born Malcolm Williamson, with whom, shortly before her death, she devised one based on Strindberg's play Easter.

What she loved about Williamson, she confided, was that, like Britten, he adored the intellectual tussle, teasing out fragments of settable opera text amid verbal battles and endless gossip. Outwardly dry, Hoddinott was privately warm, hospitable and art-loving; whereas Williamson was publicly uproarious, gay, and life-enhancing.

Larger than life, Williamson had met both Pipers through Britten. "He was great fun," Myfawny recalled. With the Pipers, fun was what mattered - amid bringing up children, plus a staggering workload. Each of John's illustrated books – such as the famous Shell Guides to Britain - highlighted those places he made his own as an artist: resplendent and surviving (cloudy Royal Windsor, aqua-tinted Brighton); faded and forgotten (Dungeness, Selsey, Renishaw); or - in darkling browns and greys - those Welsh landscapes, notably Pembrokeshire, whence Myfanwy originally hailed. The pair found a modest clifftop cottage on Strumble Head and Piper had an outhouse studio. For John it was almost 60 years of relentlessly productive life, lived to the full.

Parallel lives are surely murder to write. With two geniuses, how do you encompass even one? What's crucial is that Spalding's double biography goes that extra mile: no one, hitherto, has addressed John and Myfanwy's lives head-on as one. Has she carried it off ? In the main, yes, even if unevenly. She has triumphantly knitted together all the multifarious Piper aspects – the art, ceramics, writings, jazz, jokes, fireworks - in chapters that, while jumping around, are a well-mapped-out response to a tall literary order.