There is some Bristol footage on the content Pathe recently made available on their YouTube channel -
This is some of the bits I could see from a quick search, a thorough review would probably find more -
Mostly fleeting glimpses, I am afraid!
409 at Earl's Court -
The Big Drive - Technicolor (1966) - YouTube
407 at Earl's Court -
The Motor Show (1961) - YouTube
406 Zagato at Earl's Court -
Motor Show (1959) - YouTube
400 at Monte Carlo -
Cars Rally At Monte Carlo (1949) - YouTube
411 in 1969 -
Special ! The Motor Show (1969) - YouTube