This is how little space there is behind the screen I put in front of the doorway in the side fence. Guess what, last night? It didn't come in this way, it must have scaled the fence, but it managed to scrabble its way through to get out! So this afternoon after playing golf and doing some shopping, I didn't relish the task of resolving the problem. Fortunately, I still had the little door I made for the doorway, so I cut a bit off with my jigsaw and reduced the size of the doorway. Here's the video
No foxes in the garden last night. The alteration to the doorway presented no problems for the hedgehogs. Here's a screen-shot of the back-end of one going out. It's only a short-term problem. Fox cubs grow very quickly, the ones born under our summerhouse in March 2017 had left home and become independent by the 21st of May. The last sighting of them in the garden. So they would soon have been too big to get through the doorway anyway. But I didn't want them disturbing the hedgehogs, although they didn't seem to upset their routine. Two were using the feeder as normal and wandering around the patio looking for live food. We might not see the foxes again, given that there's nothing to eat in our garden.
It's odd to me how your foxes come so close to civilization and don't appear to be leery of humans. Over here, if a fox comes into town it's either sick from eating something poisonous or it has Rabies.