Shirley Collins writes like she sings. Simple, direct and somewhat understated. She has a naivety of style that belies the knowledge and passion that underpins her music and experience.

She has been a part of the folk music world for nearly half a century and her choice of repertoire and approach have influenced a great number of English singers that have come after. And she is a quintessentially English person and performer. She has stayed true to that semi-rural southern counties steadiness in face of the onslaught of seductive American and Celtic influences. She has taken her own tradition and broadened its appeal in quite often unexpected ways. She began playing the banjo, performing solo the songs of her native Sussex. Later she partnered Davy Graham, the innovative guitarist, back in the Sixties. Folk Roots, New Routes was an interesting experiment combining folk, jazz, and the music of India and North Africa. It remained a one-off album, but others went on to plough that furrow. Some of her most successful music was with sister Dolly. With Ashley Hutchings she formed the Albion Country Band, producing the lovely album No Roses, and worked at the National Theatre in The Mysteries and Lark Rise.

But before all this she travelled with Alan Lomax across America. To step out of a world of poverty in Hastings in 1953 to go off with a man 20 years her senior to the distant shores of America on a luxury liner was an extraordinary thing. “Living in sin” is a concept that is hard to imagine now, but it was very real then. There is great personal courage and individuality beneath this gently written tale. He was a giant in the ethnic music community seeking to document local performers, and they visited a vanishing world: the letters she wrote home form the backbone of her account of this remarkable journey, America over the Water. They travelled through the Southern states recording the likes of Texas Gladden, one of the greatest ballad singers in America, with a huge repertoire sung in the “lonesome” mountain style.

Alan, and his father John Lomax, had been on a similar journey in the Thirties and Forties collecting verse ballads that had never been written down. From the gentle, polite atmosphere of Virginia they travelled south into the more brooding Kentucky, to the intense Old Regular Baptists with their woodland prayer meetings, and hymns full of “angels of wrath, fire from heaven and blood filling the seas”. Collins describes the feel of threat from the preachers who disapproved of new-fangled recording equipment, and they had to decamp in haste. According to the modern songwriter Chris Knight, there’s still an element of the wild backwoods to be found in the “hollers” of these Southern lands, even today.

In Memphis they sought out jug bands. This is a particularly Southern urban style of music, where the drive and bass-end is provided by blowing across the mouth of a whiskey jug. Shirley gives a vivid portrait of an encounter with the Memphis Jug Band in rehearsal — a band that had seemingly lost its way in drink and ego conflicts. No change there, then.

In Alabama they encountered the “shape-note” of the Sacred Harp singers. This is, on the other hand, a Southern rural style of music initiated by the early settlers. Because there was little music reading, a new approach was forged in the 18th century using four shapes, circle, square, diamond and a triangle. It was thought easy to learn and apparently spread swiftly throughout the country. It has terrific drive and energy, with harmony used to great effect.

In Mississippi they revisited Parchman Farm, the notorious prison. The convicts were mostly black and provided huge profits, working from “cain’t to cain’t” — from where you can’t see in the morning until you can’t see at night. She had to deal with segregation, and when asked what she thought of “niggers”, she cannily stated that she had no experience of them, there being none in Hastings.

They met and recorded Mississippi Fred McDowell, a 50-year-old cotton farmer. His quiet strength and heart-stopping intensity made them aware that they were in the company of an extraordinary musician. He went on from that beginning to make several albums and was taken up by the Rolling Stones. He died only 13 years after the first recordings, and Shirley wonders whether the change of lifestyle was not somehow responsible.

Throughout the book her background and life weave a delicate pattern by way of interspersed short chapters. As she was a child of separated parents, the wider family had a stronger place. They were all fine singers. This back- ground of song explains some of her comfort and authority with the tradition. She was one of those young people who respect and admire the elderly. She patently loved listening to these old people sing, and they in turn took her to their hearts. What is it that makes some young people enjoy the company of age, while others dismisss it? Perhaps the answer can be found in a recognition of continuity, an ability to see beyond the moment to the broader vision.

Reading her book, I start to understand her better, and while she is typically self-effacing, she has been prompted to give away more of herself than she might have chosen. Which of course makes it so much more interesting.

If ever there was a book that calls for a CD to accompany it, this is it. There is great detail given to the discography, but to buy a big boxed set would be excessive. It’s a shame that some of these obscure songs could not be released to colour and inform the work; copyright reasons may play a part. It is always a problem with books about music; they presume familiarity with the material. But then, I suppose, it is intended to get us all to go and search it out.

After all, that’s what Shirley did.

America over the Water by Shirley Collins, SAF Publishing (£20; or £16 from Books First, 0870 1608080)

Maddy Prior will be touring with Abbie Lathe and Rose Kemp, the Carnival Band and Steeleye Span into 2006 (www.e-maddy.com/index.htm)