Subsequent to my initial request for information, I discovered that the handbrake lever for Series II E Type 2+2 Jaguars (and only for that model) is very similar to the Aceca lever - unlike other British car levers that have the release button recessed in the end of the lever, this one has the "cap" button at the end. The lever is (I think) a bit shorter than the AC lever, though. Interestingly, this lever is not shown or listed differently in the Jag parts book.