You will always know if a fox has wandered through your garden at night because it leaves its characteristic smell everywhere. It is difficult to describe this odour, but it resembles that of the weed herb robert.
The best way to learn what reynard smells like is to go for a walk with someone who already knows the odour, or to go to a zoo or wildlife park and have a good sniff; then you will always recognize the strong, musky scent when you encounter it.
Foxes are extremely common, even in towns: in fact, they are more widespread in many urban areas than they are in the countryside. They are real scavengers and obtain a lot of their food from dustbins. Although few people are prepared to encourage foxes into their gardens, it is very easy to attract them to a plate of dog food placed on the lawn at night (as long as the neighbourhood cats do not get there first). Use red torchlight to watch from your window and, with a bit of luck, you will be able to see what a handsome creature the fox is. It might scratch around for worms, but otherwise it will do no harm in your garden as long as you lock up your chickens and other livestock – foxes do not carry keys!