Austin literature and press images for new cars did not appear to show ANY sign of rubber for the bonnet rest area.
The first cars photographed by the factory did show a rubber. This was used for the Light Car road test of the 65 in June 1933.
This is the proper section, and please make contact if you have original examples, or wish to propose a different hypothesis! It would be helpful to know who has this in stock currently; please add a comment.
A post on bonnet rubber clamping plates (as below) is here.
Both sections discussed above also appear to be here.