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definitely a cat as I have seen it in the act so to speak and chased it off. It belongs to people who have recently moved nearby and I see it sat in the window all day long. I am not sure that could do anything to stop it even if I manged to catch them at home, they seem to leave early in the morning and return very late at night which is when they let the cat out. Thanks for the suggestion anyway. Also thanks ladybirder I have looked at the link and will follow up the plant idea.