Bomber's inclusion was somewhat of a surprise. Military fiction has never been that well regarded in literary circles, even though Bomber is much more than simply that. The Guardian has a report on the final short-list, which includes Muriel Spark and Mary Renault.
[Stop press] In a piece in today's Observer (online at the Guardian website), one of the judges Rachel Cooke describes the process of whittling down the long list to a short list, and her feelings towards the disparate novels she read.
On Bomber, she writes:
"I have just read 21 novels, all of which were published in 1970, and while a few could be described as polite, none was actively dull. Two – Bomber by Len Deighton and I'm the King of the Castle by Susan Hill – were so exciting, I read them at one sitting."