It's probably worth noting you can be charged with a driving offence if you're driving 60mph down a country road even if it's technically national speed limit.

Just because legally you can drive at 60 doesn't mean you're legally allowed to drive recklessly. National speed limit is basically, "you're permitted to drive as fast as you like so long as you do so in a safe manner".

the US used to have unrestricted speeds outside town. The speed limit would be "reasonable and prudent". I think 1975 the 55mph national speed limit put an end to all of that.

https://www.nps.gov/features/yell/slidefile/gatewaycommuniti...