Little devils, aren't they

I have resorted to starting off all peas and beans indoors ie in a tunnel, in 4" pots (2 beans/ 5 or 6 peas per pot) in baker's trays suspended from the crop bars, or for peas in lengths of guttering, again suspended from the crop bars. Once the plants are too big for the mice to want to eat them, then plant them out into the garden - the peas in the guttering will have a nice mat of roots, so can be slid out into a shallow trench.
I've not found that much will remove the problem otherwise, so although it's a drag I find it worth it.

Last year I had broad beans drying in the tunnel, for saving my own seed. The mice stole many of them and stashed them around the place. Of course they started to grow and I thought I was getting a free crop, but the little devils dug up and ate their seeds and left the greenery to die.