A BOOK by Nicholas Albery, Alternative Gomera: Guidebook to a Paradise Island (The Institute for Social Inventions, pounds 5.95) is an unusual guide to a fortnight's walking round a Canary Island as yet undisturbed by mass tourism. The book is crammed with useful and extraordinary information. In a section on 'social experiments,' Mr Albery writes about the El Cabrito community: 'The Austrian free-sex and emotional self-expression therapy commune, run by happenings artist Otto Muhl, bought the whole bay of El Cabrito as an arts centre . . . Now that Otto Muhl is in jail in Austria (he was given seven years for heroin offences and for making love to a 14-year-old) the whole commune has become very respectable.'