On his vacation in Great Britain, Paul came across the following speed limit sign:

It's unclear why this wasn't rounded up to a more reasonable number (10 mph, or even 7?).  Also, enforcement is questionable.  Usually in the US there is an unofficial tolerance above the posted speed limit where you typically would not be cited for speeding- say driving 56 mph in a 55 mph zone.  But in this case, would you not get a ticket driving a 7 1/4 mph, but you would at 7 3/8?  Also, measurement might be of concern, since the ability to accurately determine speeds to the quarter mile per hour is questionable.

Official British highway speed limits can be found here.  The site notes that:

"You mustn’t drive faster than the speed limit for the type of road and your type of vehicle. The speed limit is the absolute maximum and it doesn’t mean it’s safe to drive at this speed in all conditions." 

Therefore, on this road, to be safe maybe keep it at 6 1/2.