Thats a great find. Well done. I haven't managed to acquire any Class 2 coins yet. They are as you know rare as hens teeth. It's an excellent example.
I think i own that £102 copy of Mass. Came to £107 with p&p , when i started collecting i placed more emphasis on buying coins rather than books about them. As time went by i wised up , it's taken me 4 years to find a copy.
Here is the link to the Austin coin. Its a class 1b1. Mass had a cut half that spelled out USTIN. He lists it on page 86 as unknown.
https://mobile.twitter.com/detectingdigsuk/status/711679605057388545