Many free sprung English watches are of the 3/4 plate design.. Here is an example of a full plate design being free sprung..it does have a Breguet style hairspring..

John can you explain the term free sprung I have had watches that were free sprung but never knew what they were talking about is it a special hairspring??

Rob,

Basically, a 'Freesprung' timepiece, has no curb pins, regulator lever or any any form of mechanical regulation affecting the hairspring to adjust minor timing errors.
It is 'Free' from the centre collet to the stud on the balance cock.

The hairspring possibly is a special, most likely using materials which are less prone to expansion and contraction caused by temperature changes.

The curve on the overcoil is also possibly of a particular shape too, but I've not been able to determine which shapes were used on them.

Hope this helps

John, Beautiful watch, first time I've seen a full plate example, thanks for showing it to us.

Best regards
John

Thanks John

Rob,

John's explanation is great, just to add, and I am assuming you may not know. A regulator effectivly shortens or lengthens the hairspring, by moving the curb pins along the length of the hairspring. Curb pins are the little pins hanging down form the regulator..Shortening or lengthing the time it takes for the balance wheel
to complete its arc..

A long time ago, before I was smart, yeh right, I had an English Kew Certificate watch which was free sprung.. bought it for $80.00 and sold it for something like 200, boy I thought that I was coming out on that.. One of the dumbest things I ever did..