The 100S is fairly obvious by its grille shape...
There's one among these photos I copied from an old lady's photo album a few years ago:
David Shmith's Austin-Healey 100 at Bathurst in 1954. Before they had to distinguish between the 100/4 and 100/6.
There's a couple or more in this one lining up for a race at Gnoo Blas about 1959.
A 100S which raced here for some time was the Gunnedah-based Sam Miller car. Below it's at the Tamworth hillclimb...
Sam was at that time the custodian of a Lancia Lambda too. This had been driven to their farm new in the twenties and lived in the same shed until Sam's nephews, the last of the line, died in the nineties. They had, by that time, given it a nice new paint job.