Sadly, BS308, was superseded by BS 8888, which informs you of the numbers of other ISO standards. Most sections of BS308 have been replaced by separate/individual standards, and that means a lot of documents! If you can borrow a BS 8888 you should find what you want.
Title :
Guide to the European standards for engineering drawing in the BS EN series
Description :
Compares the new European standards in the BS EN series and BS 308: Parts 1, 2 and 3 by commentary on a subject basis and by cross-referencing indexes.