The British Rail Class 35 is a class of mixed-traffic B-B diesel locomotive with hydraulic transmission. Because of their Mekydro-design hydraulic transmission units, the locomotives became known as the Hymeks. They were numbered D7000-D7100. They were allocated to Bristol Bath Road, Cardiff Canton, and Old Oak Common. None of the class was named. Withdrawal from service began in 1971, and was completed by 1975. Their early withdrawal was caused, primarily, by BR classifying the hydraulic transmission as non-standard. Four locomotives were preserved.