The last of the four Routemaster prototypes was numbered CRL4 by London Transport (Coach Routemaster Leyland) when it entered service in 1957 in Green Line livery with the Country Bus Department, originally from Reigate on the 711. It remained unique among Routemasters in being bodied by Eastern Coach Works of Lowestoft, and had a Leyland engine like the third prototype, RML3. Later on, it was renumbered RMC4, and had a reasonably full life, both as a coach then a bus, mostly based at Hatfield. It had two single headlights and standard Routemaster bus blind boxes i.e. a separate route number blind at the front and a stylish grille and bonnet assembly that got replaced by the time the first standard Routemasters came off the production line. The registration number was SLT59 (RM1's being SLT56) and almost everyone at L.T. regarded it as a coach, and some even believed it would transform Green Line into a thriving, profitable coach company as an adjunct to the declining, unprofitable Home Counties green bus services. Unfortunately, growing prosperity and the explosion in car sales that brought about in the end doomed it, with staff shortages getting added to the mix and even the lovers of Green Line travel had to give up on it if they had paid employment to go to or a long wait at a stop without shelter against wind and rain.