The Willows in Winter by William Horwood HarperCollins $220 STEPPING into a dead man's shoes is always a risky business; rarely more so than for an author seeking to take up where someone as notable as Kenneth Grahame left off. But William Horwood, previously best-known for his Duncton series of mole books, has done so with aplomb in writing this sequel to Grahame's classic, Wind in the Willows. He has achieved his aim with a great deal more success than many of those who have recently sought to adopt the mantle of famous authors. Perhaps it is his previous experience writing about moles, perhaps the links with Grahame he outlines in his postscript: both grew up in Oxford; same birthday; both telling stories in an oral tradition. Whatever the underlying reason, Horwood has managed an astonishing empathy with Grahame's style without seeking to create an exact copy. He has produced a book that, while perhaps lacking a little of the magic of the original, is a worthy successor. He was inspired by his purchase of some of the famous E H Shepard artwork that illustrated Wind in the Willows - in particular, a nervous Mole trekking through the Wild Wood in a blizzard. Although Horwood knew where Mole was going, as he looked at the picture above his desk each day a different explanation suggested itself. So The Willows in Winter, in which Mole, thinking Rat and Otter are in trouble, sets out in a blizzard to reach them and falls through the ice on the river, was born. No Willows tale would be complete without Toad and when he ''hijacks'' a plane to join the search for Mole, a new series of dangerous adventures begins for him too. Horwood tells his readers it was ''the deeper level of meanings that may, or may not, exist in these Willows stories'' that interested him most. He mentions the ''clubby bachelor world'' of Edwardian England that informs the central characters and the sense of mystery about nature and life forces to which no religious or sectarian names are given. Such forces are brought to play in Horwood's own book - as Rat falls from Toad's plane, he has the unsettling experience of glimpsing ''The Beyond'', for instance. But this philosophical aspect is dealt with in a way as true to the original's spirit as are the characters, the plot and the marvellous line drawings of Patrick Benson. The publishers have packaged the book admirably - colour maps of the Willows world inside the front and back covers, the book bound in dusky blue, printed with gold, the white dust cover featuring a truly charming Benson drawing. It's not Wind in the Willows - but it isn't meant to be. It is however a new classic, a book to be cherished in its own right and for parents to enjoy as much as the children they read it to will.