I know that 1778 was a pivotal moment in the world of locks, with the Barron Patent, but did he actually invent the double acting lever, or was he the first to realise that with more than one you could have real security?
Looking at the page on the Aubin Trophy (http://www.chubbarchive.co.uk/page10.html), there is more than one reference to double acting single lever locks, e.g.

5. Marked Old English this lock has a double-acting lever that must be lifted to a precise position to release the bolt.

Further:
17. By Sanders - this has four double-acting levers.
27. By Robert Barron (the 1778 patent - his second) with double- acting levers.

and yet:

25. By Price (patented in 1774) - the first lock to have four double- acting levers. (Emphasis in original text)

So was it in fact Price who invented the modern double acting multiple lever lock? I'm going to have to go and consult some books! And I need to find a picture of this lock by Price.

(Once this is all over (Covid) I'm going to see about arranging some proper photos of the Aubin Trophy, as the tiny old ones on here are really not that useful, nor do they show off the locks! In fact, the best photo of it is the one snapped of the trophy room for the Covid announcement! https://antique-locks.com/images/ima...-HR-AT-max.jpg )