Kind of knowing the fella who owns it I think he would be more appreciative of someone letting him know to be honest. There is a massive mouse population in the area, we had some in our house and when the council came out to offer some advice, he said the only way to truly stop them is to have any hole in your walls or floors beneath 3 foot height, smaller than what a bic pen could fit through. Or you have no chance. All the cleanliness and baiting and regular inspections won't stop them if they are around. It's not always related to how clean you keep a place.