Maybe other growers have come across this before, but here's a little success story.
No matter what I've tried previously, (presumably) mice have always dug up my pea seeds before they've germinated. Last month, I covered each seed with a mini-cloche made from used tropical fruit-salad containers. They're about 3" diameter and same in height so a perfect size, and being transparent, you can see when germination has occurred. I use a hot metal skewer to make a small hole in the top and then poke a wooden kitchen skewer through the hole to secure them into the earth. A bit of soil around the perimeter keeps everything firmly in place with no gaps for anything to get through/in/under or whatever. A row of them looks a bit odd but so far, I've had 80% germination rate and no signs of any disturbance. Hope others find this of help and good to hear what others do.