Compared to the earlier Wallasey twins, the "Mountwood" and "Woodchurch" were highly advanced. They benefited from an injection of cash from both Birkenhead Corporation and the Joint Tunnel Committee. They were given special Crossley eight-cylinder engines which were fitted with gears and automatic air brakes. New style telegraphs by Chadburns were designed which had a facility for braking the engines for rapid reversal, the telegraphs were part of a brand known as "Synchrostep" and were all originally unpainted brushed aluminium with shiny brass rimming. "Overchurch" had the same telegraph 'heads' however they were fitted into the wings and main control position in specially built units which also had instruments fitted to them. They entered service in 1960 and were a hit with ferry passengers. They were light, modern and boasted the latest in marine navigation equipment. They were given an orange and black funnel livery, with a red band just above the rubbing strake. In their early years of service both the ferries carried rope fenders to protect the strakes.