Jim Boyd raced a Volvo 1800S in the 1966 and 1967 Three Hour Races at The Wills meetings. Ian Green co-drove in '66 (11th) and Brian Rice in '67 (9th).
I don't know if the the same car was used in both outings but I seem to remember seeing a photo of what must have been the '67 car that looked white in colour while the attched photo of the '66 car is clearly a darker shade - probably maroon as you say.