OBNB doesn't sell books, but you may be able to find a copy at one of these websites:
The first 25 years : history as mirrored in advertising of Shell-Mex and B P. Ltd, 1932-1957 by Shell-Mex and B.P. Ltd.. Published by Shell-Mex & B.P., Ltd in 1957. Publication and catalogue information, links to buy online and reader comments.