What Alex has just achieved is the CTT 10 mile competition record. That means he's done the fastest 10 miles in an open time trial run under CTT rules: those include an out and back course to within a certain tolerance of height and distance, riders off at minute intervals, races running on courses on which the traffic has been determined not to exceed a certain level etc etc. Someone has probably done a faster 10 miles on a bike on a straight out downhill. You're allowed to do that in an
RRA record attempt but their records start at 25 miles. Incidentally, Chris Boardman used to hold an 'unofficial' comp record because he went faster than the then current comp record in a club 10, so it didn't count as it wasn't an open event.
No, it doesn't include other countries. However, TTing is a very British pursuit and I haven't heard of anyone going faster under any remotely similar rules, so it's a pretty safe bet that nobody has done so.