THERE is a vast network of public footpaths, bridleways and ancient tracks running through Britain, and a map which is available from the British Tourism Authority (BTA) in Hong Kong gives details of more than 60 walks. They range in distance from the Beacon Way, some 30 kilometres, in the West Midlands, to the Southwest Coast Path (See map, No. 1), covering 962 kilometres. The Pennine Way (No. 2), covering just over 400 kilometres, is the most famous. Scotland's West Highland Way (No. 3), a total of 153 kilometres, begins just outside Glasgow and passes through some of the country's most remote and rugged countryside. Other walks of interest include the Pembrokeshire Coast Path in Wales (No. 4), which is 290 kilometres long, and the ancient Icknield Way (No. 5), 160 kilometres. Contact the British Tourism Authority at Room 3005, Alexandra House, Central, for more details, or phone 522-0044.