M's 1954 Rolls-Royce Phantom IV in On Her Majesty's Secret Service

In the 1969 film On Her Majesty's Secret Service, we get a very brief look at the black Rolls-Royce owned by M (Bernard Lee), Head of the British Secret Service MI6.

The impressive vehicle is parked outside of M's private residence Quarterdeck, next to the green 1969 Aston Martin DBS of James Bond, who is visiting.

M's car is a 1954 Rolls-Royce Phantom IV by H.J. Mulliner, a vehicle that even by Rolls-Royce standards was extremely rare.

One of only 18 Phantom IVs produced and those were almost exclusively delivered to world leaders and heads of state.

Five were supplied to high-ranking members of the British Royal Family, three to the Government of Spain, three to the Hakim of Kuwait, and two each to the Royal Family of Iraq and the Shah of Iran.

This particular Rolls-Royce was built for HRH The Princess Margaret, sister of Her Majesty Queen Elizabeth II. 

Princess Margaret owned the car from 1954 until 1967, and actually drove it herself quite regularly. The car had registration PM6450 and a blue police light and heraldry on the car.

At its retirement in 1967, the police light and heraldry were removed, and the Rolls-Royce consigned to a London dealer. It was sold to A.W.D. Adams, owner of a limousine service in Essex, for whom it was registered as "302 HYP", which is the license plate we see in the film On Her Majesty's Secret Service.

The car was probably rented or borrowed from A.W.D. Adams to feature in the 1969 film On Her Majesty's Secret Service.

For more than thirty years, the Rolls remained in the ownership of Adams. In 2003 it was acquired by American collector Robert Shaffner, who was able to reunite it with its former Royal registration, which had become available following Princess Margaret’s passing. He was also able to refit a correct police light and heraldry.

In 2008 it was sold again, and in 2021 it broke a record at a RM Sotheby's Car Auction for the most expensive Rolls-Royce Phantom IV when it sold for CHF2,255,000 (approx. $2.5m).

In the same film, Marc-Ange Draco also drives a Rolls: a 1968 Rolls-Royce Silver Shadow Drophead Coupé (Mulliner Park-Ward) to be exact. This car is used to transport Draco, James Bond and Tracy in several scenes.

Sources: 
RM Auctions
IMCDB
Wikipedia