Thanks Chaps
It is indeed a Leyland and to give it it's full name Leyland Royal Tiger Worldmaster! It is a twin decker I believe and travelled to all the major GP's of it's time, mainly in Europe, Spa,Monza etc.
I am lucky to live close to Bourne where BRM developed and built their cars.
This picture was taken at the anniversary of BRM winning the Drivers title with Graham Hill when all the serviceable cars were run through the town centre.And it wasn't a parade!
These colour pictures (not Pentax is that allowed here?) are again in Bourne and are of the famous V16 and the transporter with staff and relations of BRM.