Liza, I am afraid that you will end up in a world of bother if you do catch them. I would suggest using a bike cover or failing that hire a garage from the council. Do you have no way of getting the bike under cover? Mine lives in my kitchen.

Pity about the police response. A good few years ago I caught someone trying to pinch mine, called the police and they turned up in a couple of minutes, we then spent some time driving round the neighbourhood trying to find them.

P.S. I have a bike cover you can have if you like, it's a good study one. PM me if you are interested.