James Dixon & Sons question

Hello, I received this beautiful vintage flask from a friend and I’m trying to identify the markings.
Not sure about the “D” above the Made in England or the 72 & E.T next to the 17oz marking.
Thanks for any help

The D may simply stand for Dixon or it could perhaps be a private date code. As for the 72 and the E.T I have no idea, but probably of no particular significance.

Phil