We think it was mice Snadger, when we dug over the area for the strawbs and rasps we found quite a few tunnels, took advice from the council liason and she said field mice. She also said with the rural location it was impossible to stop them coming onto the plot, but that they werent usually too much of a problem.
Having said that we did tip a load of water down every burrow we found and then blocked them up tight with soil. With double digging those beds I think we may well have destroyed any burrows, so will have to wait and see whether they return or not. The only areas we havent double dug yet are the last large bed near the pond, under the shed (which needs a new floor anyhow, so will be tackling that sometime early in the new year) and the highly raised bed at the bottom of the plot where the rhubarb and brambles are (which is very overgrown and full of nettles, brambles, russian vine and raspberries. The current plan is to tackle that once we have all the main beds dug over, and to put some supports in and train the brambles over them, along with planting our loganberry and possibly a couple of gooseberries down there, with a path down the middle, so we will find out what the score is when we tackle that area!
Oh, and the damage to the strawbs turned out to be slug damage, so we've mulched under all the strawbs and planted through weed control membrane in the hopes that this will help keep the slugs off them!
If we find evidence that they are still around then we'll do something about it then!