I have to correct myself partly on one point:

I said before:

"2. The "Double" concertinas should NOT be regarded as -"similar in appearance/ergonomics to English models"
The handles suggested for them are rather analogous to those on Anglos and common Duets ( Maccann, Crane etc )"

The tutor for the Double by Joseph Warren, to be found here:
http://www.concertina.com/double/Warren-Double-Tutor.pdf

shows and arrangement with thumbstraps but no fingerrests and says on page 2 "Holding the instrument" "leaving the first, second,third and fourth fingers ready to act..."

The arrangement thus is similar to the William Wheatstone 1861 variant but still NOT to be regarded as -"similar in appearance/ergonomics to English models"

Yet, nothing is said in the 1844 patent papers about hand rests on the Double and I have a vague memory that I have seen one instrument in real having the common Anglo/Duet arrangement I talked about. I would not be surprising if both ( or more) concepts were tried on the limited number of instruments in use.
Would be interesting to know how many actually were produced. To my knowledge just one example ( maybe a prototype ) has come up of the William Wheatstone 1861 patent model,