NEXT Thursday, 11 August, is the centenary of the opening of the West Highland railway line linking Glasgow with Oban, Fort William and Mallaig - one of the most scenic in Britain. To mark the occasion, Case Publications (041-221 5521) has brought out a definitive guide, The West Highland Line. As well as being a compendium of interesting trivia, the book includes a good selection of walks that can be made from many of the stations along the way.