When we moved house fifty years ago, the first time my dad came home from work he walked into the wrong house - it was not usual to lock the doors then - and surprised a neighbour's wife, though it was in the kitchen not the bedroom, and at a distance!!

The houses on the road were all identical. Later the front doors were painted in different colours. Four or five, done in sequence all along the road. It still made very little difference in the dark.