A brand new Standard Class 5 comes out of the works on 1st May 1955. No.73076 was destined for Polmadie and it stayed there until withdrawn in July 1964. The tri-tone whistle, clearly visible behind the chimney, was operated from the cab by a cable running down the right-hand side boiler handrail. These had an unfortunate tendency to stick open after a while and eventually to disintegrate. One on No.73000 jammed as the engine entered Ampthill tunnel and sounded continuously until the train reached Flitwick, some two miles away; inevitably many were quickly replaced with a less risky type. Engines from No.73100 onwards had a monotone whistle fitted horizontally on top of the firebox.