Here's a new Brake Master Cylinder (3/4") for the following models from Austin -

AUSTIN

Austin A40 "Cambridge"  (** 1954- 56 Only **)

(** Only for the Cambridge **)

(You'll need to re-use your old rod, it's an easy swap as it's only held on by a circlip).

** Don't buy this for the A40 Farina, A40 Devon, A40 Dorset, A40 Somerset or A40 Sports **

** All the other A40's are completely different - You will be wasting your time **