RAF slang for gash navigator who has to follow railway lines in order to get back home. In reference to popular 19th century guides for rail travellers produced by George Bradshaw.
Nigel you're such a Bradshaw!
"That bradshaw just loosened me up with his profound nature and velvet voice. We gotta go!!"
"God, he talks the talk but he sure doesn`t walk the walk. Total Bradshaw."
ex. Everything older than 5 minutes is unknown and soggy; "old people music"