The date of the book print is immaterial to a collector. The values may be outdated, but the facts and plating data is essential reading and reference. Also the specialist data regarding franking and colour variations is a must if you want to get everything.
A very detailed Stanley Gibbons catalogue. This is one catalogue that does not need to be a new edition, unless one is only interested in prices of stamps. The edition I bought was the 7th edition, published in 1983 and apart from the costings the information is perfectly suited to collectors' needs, because after all, there are not going to be any new issues of Queen Victoria stamps !
The copy I bought was in excellent condition and at a very fair price.