The beautiful interior of the Phantom V which I posted earlier was a James Young model from around 1968. James Young was another London coachbuilder that was established in 1863. I personally have always liked the James Young designs more than the Mulliner Park Ward ones - they are more elegant and stylish IMO.
Just on coachbuilders:
After WW2 the market for coachbuilt vehicles was very small. In 1968 when the Phantom VI was launched it was already a relic from a different era - still made with a separate chassis and a completely hand built body.
The famous English coachbuilders were Gurney Nutting Ltd, James Young Ltd, Hooper, Windovers, Barker, and H.J. Mulliner.