After oko94 posted Lance Macklin I had another look and he co-drove Ian Metcalfe's Bentley at Spa in 1949.
That Bentley was the Barnato-Hassan special in a two-seat version which either was or became what was known as "the whale". Keith Schellenberg owned it and returned it to its single-seater form which it still has.
Here it is in its early form (with Oliver Bertram at the wheel):
and with Dudley Froy:
Not sure when this one is, but perhaps after the Schellenberg rebuild but before he painted it green
and this is how it looks now:
