Abstract Five types of British woodland are particularly important for habitat conservation, namely; relicts of medieval wood-pasture management; ‘native’ pine and birch woods in the Scottish Highlands; some coppices on ancient woodland sites; woods on inaccessible sites; and woods with a long period of natural structural development. The case for these priorities rests on the concepts of non-recreatability and past-naturalness, which are discussed. Together these woods form no more than 20% of existing woodland. Comparison with woodlands and forestry practice in Czechoslovakia and France shows how much the definition of priorities depends on the particular climate, woodland history and current forestry practices of Britain. The same concepts can apply to other semi-natural habitats in some circumstances.