I remember reading Alex Henshaw's book and he used to find his way back to Castle Bromwich through 8/8ths when he had been test flying Spits by looking for the rise in the stratus layer caused by the hot air in power stations. He knew where the local ones were and could drop out of the clag right over the airfield.
I never forgot that and it does actually work. There are two power stations near me and flying on top you can see two huge bumps where they are.