I recall that when it came out in '76 I had quite a job getting hold of it and had to order it through an independent bookshop. Never realised they did a 1984 reprint. The more recent Vols 1 and 2 has Vol 2 with the main content of the old paperback plus some more recent selections from Stuart Nicholson and the others, to 'bring it up to date'. Vol 1 covers 'early jazz'.
The '76 book was right on the ball with some of its selections (e.g. 'Africa Brass', JR Monterose 'The Message', Al Haig 'Jazz Will 'O' The Wisp') and it was pretty well guaranteed that anything in there would be an excellent listening purchase. The only problem at the time was tracking down some of the music (e.g. Monterose on Jaro International vinyl sourced in 70s UK = more chance of winning the pools).