Ruston single cylinder horizontal four-stroke diesel engine size 11H. Originally installed at Taplow Repeater Station near Maidenhead and one of a batch built to a GPO order.
Driving two G.E.C. generators in tandem by means of a shaft extended from the flywheel. At 210rpm one generator produces 22/30 KW at 22/30 volts, 1,000 amps with the other (No. 84850) 11 KW at 150/220 volts.