I think the XXXX could be Coad by the name of its pilot, I have found a photo that refers to the car as Coad Special so you must want Coad Vauxhall Special. You are right the photo was taken in 1960 in Phillip Island but the car is dated in 1956 as its ifirst races, because although planned to appear late in 1955 its first outing was at the Albert Park International GP in March 1956 where it ran both weekends with average results.
I have found a nice coloured photo: