Re: Neighbourhood Tomcat is harassing my female cat
I bet it is through a cat-flap.
The ONLY way to prevent this tomcat from coming inside your home is for there to NOT be open access. You need to install a cat-door that only allows your cat in, build an outdoor cattery (like a dog kennel/run) to keep your cat safe when she uses her flap to go outdoors or block it off completely and you personally monitor your cat's comings/goings to be sure no unwanted visitors crash your pad.
This is not the tomcat's fault that you have given him access to your home. Your job now is to figure out a way to deny him entry. As long as there is a flap that allows anything and everything to pass through it, this cat will continue to make-himself-at-home.