Ah, you have to love a book that makes you laugh, don't you? I missed out on ''The Exiles'' when it was first published in 1991 - too old to buy children's books on my own behalf and too young to have children of my own to buy them for. And I really did miss out. The four Conroy girls are utterly hilarious. Saddled with well-meaning but rather ineffectual parents who won't drive cars or own televisions, they rely largely on books for entertainment and their overfed imaginations lead them to make a virtue of their differences from their peers. They refuse to conform. Phoebe, Rachel, Naomi and Ruth leave a trail of devastation behind them wherever they go. From bee stings to paint stains, they are hard work all round.