British Rail Train-Crew Manual - Class 37 - Drivers Fault Finding Data And Charts - Dual Braked Locomotives
Issue Date: Unknown   -   BR 33056/11.

More information can be found here Wikipedia - British Rail Class 37   The Class 37 Locomotive Group
More Information Regarding Preserved Class 37 Locomotives can be found on the following websites:  Preserved-Diesels   SRPS Diesel Group