Mona Nath:  Re this car, Michael Hay, in his book Bentley: The Vintage Years, 1997, states: "Eng AX1665 removed before sale and replaced by HT1630. Last heard of 1966." We are not able to figure out the possible role of Eng AX1665 (since the original documented engine for this car is HT1630)
Perry Margouleff: Yes, I know Michael Hay and have read his book. The engine was rebuilt and remade in 1968 by Paul and Andrew Wood for The Avengers with the original sump remade.

Mona Nath: Do you know when the car got engine no. DE1210?
Perry Margouleff: The car has had the engine no. DE1210 since 1968.

Mona Nath: Is there any other info about the car's history you would like to share
Perry Margouleff: This car has also appeared in the Hammer film "The Ghoul"/"The Night of the Ghoul" (1975) and has lived a quiet life for the last 40 years. I have done a mechanical restoration over the last 2 years, but have left the car as original as possible.

The car was privately owned and only changed hands a few times over the years. Most notably, it was the first car that P&A Wood twin brothers, Paul and Andrew Wood, worked on at the beginning of their career. They performed this work for a film company that was using the car for the TV show, "The Avengers." Patrick MacNee can be seen driving this car in many of the episodes. In the 1990s, it spent a long period of time on display at the Coventry Motor Museum.

This car was purchased by Perry Margouleff in 2015.

"I found information about the 3 Litre Bentley used in the TV series "The Avengers" as one of John Steed's vintage Bentleys.

This car also appeared in the Hammer film "The Ghoul"/"The Night of the Ghoul" (1975). There is a midnight car race between the Bentley and a 1924 Vauxhall at the beginning of the film, later in the film the Bentley has an accident."

1927 Bentley 3 Litre in The New Avengers, TV Series, 1976-1977

1927 3-Litre Racing Green Bentley.

This car appeared in a total of 12 episodes of The Avengers. In the first 6 of these it bore the registration plate UW 4887 (its predecessor), which actually belonged to KL3590. In its second 6 episodes it had its correct registration, YT 3942. These were shot between Jan 1966 and Aug 1967.

YT 3942 in The Avengers, TV Series, 1961-1969
(Comment found on IMCD website: "Steed used 4 or 5 different Bentleys, though he and Emma spoke if he had only one...")