I think all the HD 11" brakes. My a12 is definitely manual adjuster. Strangely, the ten inch drums on my 62 have self adjusters.Were they all that way? or was that only on the A12 cars ?
And the power disc's would have had ten inch drum rears, with self adjusters.According to my books, B31 is 11'' manual adjustable drum brakes.
It also looks like the car didn't come with power brakes either, or it would have had a marking under B51 which would have automatically made it power disc brakes.
I hope this helps........