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Thanks for your answers. This is what I thought too but wondered if I contacted her she'd make a decision either to confine the cat to the house so I'd set up a cat litter or not let cat have access to the house. It really does smell so I can imagine the work she'll have to do cleaning down all furniture etc to get rid of it. The cat is soft and doesn't guard her territory and one cat that I know of comes in and eats from her bowl hence why I need to go every day.
Yes, there does seem to be some raving parties in there. This is the first time it's like this but her absences must be giving these cats confidence....