Given where my allotment is I don't think I can keep them out, and given that I'm doing this for fun I'm not going to use poison (apart from worrying whether my daughter or her friends will play with it).
I might change the way that I grow them. If not I should probably harvest them sooner and more often, easy with no-dig, as this would save more and the disturbance might keep them away.
I guess I was hoping someone knew of 'mousebane' or something similar.
Jeremy