Interesting GB. My copy, 7th edn, published in 1961 by Iliffe Books Ltd (exactly 30 years after the first edition) only contains 2 ads - a full page for Triumph, and a full page for Burman, at the end, after the index. Mine was 6/6d when I bought it new aged about 14, and it says on the hard front cover - which shows an AMC twin having one of its separate cylinders being removed or refitted - 'over 188,000 copies sold'. The back cover advertises other books in the Motor Cyclist's Library collection published for The Motor Cycle by Iliffe. A useful little book, as we have both said before on here I think.