A feral cat problem

Question: What can I do get rid of/ keep away a feral tom cat who arrives at my house everyday?

 

For months now a black tom cat we have nick-named Bob, has arrived at out house, usually looking for food. We don’t feed him per se, but there is always dry food available to our cats and Bob thinks nothing of entering the hosue to scoff their wet food when the humour takes him. This has to stop. He stinks to the high heavens and  as he is ballsy enough to enter the house, he thinks of it as his. For those of you who have never had to deal with a tomcat, they spray their ‘territory’ to let other cats know they’re in the vicinity. Unfortunately for us, Bob includes our home as part of his ‘vicinity’ and I’m heartily sick of him and his reeking eye-watering spray.

Of course our two remaining cats are afraid of him, whihc is understandable as they are not intact males and have not had to fight for anything more pressing than a warm lap for years. The Marklar and Bob got into a hell of a scuffle on Saturday after Bob broke into my office where the Marklar was asleep in my chair. This is a problem, it means we can’t even leave the office doors open to let some air through the house without Bob using the opportunity to come in a help himself (he spent a night asleep in the office a few weeks back when he hid at lock-up time). The Bigger of the Cats, toothless and too old to be deaing with this kind of nonsense, has taken to spending more and more time on my bookcase, rather than lying sprawled in the garden in the sun, which he likes to do. It’s not fair on either of my two cats.

Short of catching Bob and carting him off to Diamond Marks to have his balls removed, is there any way of keeping this cat out and away from our property?