Queen Annes are a favorite of mine, so I'll pitch in my 2 cents.
The term unfortunately is used for several totally different designs.
My preference is that it be used for one design that is unique and deserves a name of its own - and that is the "integral-breech lock" with external cock. In other words, the breech (and sometimes the whole barrel, if not a "turn-off" barrel), is made in one forging with the lock plate and the trigger plate.
This results in a three sided affair - bottom, right side, and front, which is the breech. This soon evolved into the "boxlock", which puts the cock in one piece with the tumbler and brings it out the top of the box - right in the sight line, making it strictly close range gun.
The Queen Anne is one of the most graceful muzzle loader designs. The design Pedersoli and others call a Queen Anne is just a normal side lock with the front end of the stock cut off to allow using a wrench to remove the barrel.
The Queen Anne was promoted as a cavalry weapon at first, as the turn-off barrel design gets a lot of power out of the powder (they were still shooting at guys in armor when the design first appeared), and it also prevents the ball from jostling loose when pounding along on horseback. Alas, it didn't work out, as it was too cumbersome to load - if there wasn't some form of restrainer, the barrel could be dropped, after which you might as well throw the rest of it at the guy with the pike.
They must have been expensive to make because of the complicated forging, and most are of high quality to appeal to the gents who had enough cash to not quibble about the price.
OK, I'm running out of steam - if you want more, pick up a copy of John Burgoyne's lovely little book "The Queen Anne Pistol".[url]
http://dogbert.abebooks.com/servlet/SearchResults?an=burgoyne&y=16&tn=queen+anne&x=50[/url]
Blackley
[url] http://www.blackleyandson.com/[/url]
and The Rifle Shoppe both make kits.
I've heard that Pedersoli's "Queen Anne's" with turn off barrels had problems with the barrel coming unscrewed.
The time frame you cite is right on for the "integral-breech lock" Queen Anne. The design apparently started some years earlier (there was at least one made with the "English Lock" horizontal sear design). The Mortimers made some in the early 1800's, so you don't have to cut off at 1730.
Here are a couple of views of one of mine, including a view of the "other" side.