British Rail Train-Crew Manual Class 97/7 Locomotives (Battery Operated)
The 97/7 Locos consist of a pair of motor coaches converted form class 501
Euston - Watford DC EMU stock designated A & B.
The former passenger compartments contained sealed Lead Acid Batteries and
Issue Date August 1981 - Issue 1.
More information can be found here
British Rail -
Wikipedia - Class 97 Locos (BR)