> That must have been fun for the Romans here in Scotland - an hour would be roughly two and a half time as long in winter as in summer!
Mechanical clocks in Japan were designed to handle those situations:
> Adapting the European clock designs to the needs of Japanese traditional timekeeping presented a challenge to Japanese clockmakers. Japanese traditional timekeeping practices required the use of unequal time units: six daytime units from local sunrise to local sunset, and six night-time units from sunset to sunrise.
Look where the sun is, remember where it is at sunrise/-set (much easier if you're outside every day) and then mentally divide the sky into segments and just ballpark it.
That must have been fun for the Romans here in Scotland - an hour would be roughly two and a half time as long in winter as in summer!