I don't think there's a link on our site to this useful publication (apologies if it is and I've missed it).
So here it is.
It's 756 pages cover all the Lucas electrical equipment produced from 1945 to 1960.
Although the Ace is detailed under the Equipment Specification by Vehicle section, unfortunately the Cobra didn't come into being until a few years after this publication.
If you've ever wondered what exactly the differences are between the 23 (yes 23 !!) variants of the Lucas Rotary Panel Light switch then you should find the answer here.
http://mgaguru.com/mgtech/books/lucas400e.htm
Phil