One of the BBC's early Outside Broadcast vehicles, MCR 1 (short for Mobile Control Room), was built by the joint Marconi-EMI company and delivered to the BBC just in time to televise the Coronation of George VI and Elizabeth in May 1937. MCR 2 was identical to MCR 1 and was delivered in the summer of 1938. The MCRs could handle three cameras. Initially, they were standard Emitrons, but were later supplemented by Super Emitrons, which performed much better than the standard ones in low light. The MCRs were built on the chassis of an AEC Regal single-decker bus.