The first prototype RM passing Nelson's Column when in service on route 260, date unknown but sometime between early March 1957 (6/3/57) and end July 1959 (31/7/59). After overhaul in late 1959, RM1 spent the rest of its time with LTE as a driver trainer, and retained this frontal arrangement until early 1964 when the front end was rebuilt to confirm with the standard Routemaster.

<i>AEC Gazette Nov-Dec 1959</i>