The fox comes to the garden near the back door each night and now appears to be walking without difficulty (assuming it is the same fox). It is very cautious when it is close to the house - as you can see in this video clip from last night. It snatched the food from the dish and ate it at a safe distance.
A few minutes later the fox also took a fancy to the dish and took that away as well!
A little later still the fox returned (without the dish), presumably hoping I had got up in the middle of the night to put out more food. Either that or another fox was attracted by the smell of food.
I don't know how far the dish was taken as I haven't found it yet. If it is still in the garden it is well hidden. Maybe the fox is doing the washing up.