Rolls-Royce
Phantom IV of Princess Margaret (H.J. Mulliner, chassis 4BP7)

Why it matters

Chassis 4BP7 was built for Princess Margaret and is one of only 18 Phantom IVs, the only Rolls-Royce ever fitted with an inline eight-cylinder engine. The model was supplied only to royalty and heads of state, making it the hardest Rolls-Royce to acquire.

How rare is it?

Six separate kinds of rarity – never combined into one number.

Each kind of rarity is rated separately and never combined.

Production

Every figure says what it counts.

Independent counts (e.g. engine and colour) are never combined into a calculated figure. Surviving examples are never presented as original production.

History

4BP7 was the 15th Phantom IV produced; its right-hand-drive chassis was delivered for testing on 14 February 1954 and then bodied by H.J. Mulliner to their design number 7368, with the customer noted as 'Baron Montaigne', although Rolls-Royce records name Princess Margaret. It was finished in black with power windows and division, a glass roof panel, a blue police light and mounts for heraldry and a flagstaff.

Because she liked to drive herself on occasion, it received automatic transmission and an adjustable cloth driver's seat. After retirement in 1967 the car was sold through a London dealer and for over thirty years was hired out by a limousine service in Essex.

Technical specifications

Engine

Transmission & drivetrain

Chassis, body & dimensions

Performance

“Not yet verified” means no source has been checked for that value yet. Nothing is estimated to fill a gap.

Identification guide

How to tell an original from a replica or later conversion.

Identifying features are the 4BP7 chassis number, H.J. Mulliner design number 7368, all-black finish, a Pegasus mascot on the radiator, two radios (the rear one muting the chauffeur's), an adjustable rear seat that moves forward, and the original blue light and heraldry mounts above the windscreen header.

Sources

Each number links to the exact facts it supports.

1. 1
   RM Sotheby's – 1954 Rolls-Royce Phantom IV Limousine 'Princess Margaret' by H.J. Mulliner Level B

   • 1 individual royal car (model total: 18 Phantom IVs)

   Accessed 2026-11-12
2. 2
   1954 Rolls-Royce Phantom IV Limousine Princess Margaret by H.J. Mulliner, A Passion for Elegance 2021 Level C RM Sotheby's

   • inline eight-cylinder engine, a refined version of the B80/81
   • inline eight-cylinder engine
   • fitted with automatic transmission
   • chassis derived from the Silver Wraith, significantly strengthened
   • wheelbase of 3,683-milimeter

   Accessed 2026-11-12