> What other gov’t during the same time period has lasted as long or longer (none that I am aware of), let alone has produced prosperity, etc. to the same extent?
The constitutional system of the United Kingdom is over 1000 years old.
There is no plausible entity arising from that arrangement that one could refer that has survived even 1/10th of that time intact. Not even counting the devolving of numerous other additional territories.
Including the Sovereign, or Parliament.
It has kept the title, but so has France and how many Republics are they on now?
> It has kept the title, but so has France and how many Republics are they on now?
The US has also kept the title of the Senate, but I'd argue that it's been a very different institution since the 17th Amendment. Also, the Federal govt. until the Great Depression was much more hands-off (witness the overuse of the Commerce Clause since then.)
I'm not sure that the Founders would think of the present-day Republic as the same as theirs.
The constitutional system of the United Kingdom is over 1000 years old.