I realised that it was highly likely that damage like this could allow fungal infections to enter the leeks, so decided that the worst-damaged ones had to be used up very soon.
Two leeks is enough for a serving for the two of us, so two of them came up straight away. More will have to follow soon.
These "Toledo" leeks are actually quite decent specimens. The table on which they are laid here is 5 feet (1.5 metres) long.
In order to make the leeks useable in the kitchen I had to strip off several layers, but I was still left with a couple of quite decent leeks.
You can see that the one on the left had been squashed by the offending animal and severely bent, but I straightened it up!
For now, I have draped a piece of lightweight anti-butterfly netting over the remaining, rather battered, leeks. Maybe it will deter the foxes; maybe it won't...
I'm beginning to think that I am going to have to buy some more nets and poles in order to cover ALL of my raised beds. It is animals that do most damage in my garden, not diseases or weather.