Definitely mice byt the sound of it they love the broad beans, the one inch holes are the clue, the only answer is to pre sow in pots I use peat pots in my lotment greenhouse, and when I sowed mine last year I lost a lot to mice, the oldtimers on my patch told me 'flood sow' in two inch deep drils with about ten seeds per 6 inches of trench.
Thankfully our local farmers merchant (Good ole mole valley farmers) sells beans for about 1.50 for half a kilo (aquadulce)) so we can afford to be generous.
