Pesky invaders

For the best part of a year we have been doing battle with a persistent invader.
It has dug under the fence in several places and comes into the garden and digs holes in the lawn.
The trail camera occasionally picks up a fox but we’ve never actually captured an image of anything when we put the camera near the excavation.
A sharp spiky metal grid deterred it for a while but it came in another way then dug its way out avoiding the spikes.
The apple tree pruning provided a large number of branches to be hammered into the ground.
Failing that the Jasper Carrot solution with a good torch, a 12 bore and a revolving chair may be the answer!