I have a book by John Le Carre, titled, 'The Looking-Glass War'. I have tried searching the internet for the value of the book but with no success. This book title does not show anywhere on the internet. This edition was published by Pan Books, Ltd, in 1966. It was first published by Wm. Heinemann Ltd in 1965. Is this a rare book?

http://www.amazon.com/Looking-Glass-War-John-Carre/dp/0743431707/ref=sr_1_1?ie=UTF8&qid=1298116617&sr=8-1

It's also in public libraries throughout the world, in hardcover, paper, and electronic formats.