Trouble is - the little critters can get through the smallest of holes - I've heard it said that a hole you can poke a pencil into is sufficient...Normally, I would recommend removing food sources as they don't hang around if they can't find any, but you already have this one covered off by the sound of it.We also have a Victorian house and suffer on and off from the occasional mouse.In fact, we are suffering from what seems like an entire family at the moment and they are proving troublesome to get rid of due to my own laziness in respect of food sources and not setting adequate traps etc.In the past they have always b*ggered off reasonably sharpish in the face of a cleanup and a couple of well placed traps.I do wonder however how much the success of previous eradication campaigns depended upon the presence at the time of between one and three moggies.Now that we have no cats maybe the mice don't see the point of getting lost quite so clearly!And therein lies my suggestion to you - get a cat... but don't overfeed it - keep it keen![Not an expert - just have some experience.]
Tony Colliver ● 4884d