It's a Bentley 4.5 Litre from 1939.
"In 1939, when production of its new Mark V Bentley model had begun, Rolls-Royce embarked upon a programme of engine rationalisation that allowed for just three types of powerplant - the four cylinder B40, six-cylinder B60 and eight-cylinder B80. Rolling test beds were required, for which four MKV chassis were laid down and their wheelbases extended by 4 inches so a division could be included in the specification. Each was bodied by Park Ward and the first three fitted with B60 engines, while the fourth received a B80 one. This car, chassis number 3B50, was a member of this experimental quartet and received B60 engine No.11."
