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Thanks guys - jno, I did NOT need to see that, thank you, I'm jittery enough today ;-)
Thanks for pointing me in the direction of china dolls post - I did search before I posted this, honest, but I seemed to miss that one.
My skin is crawling as I type this (not literally, thankfully!), but I am now quite reassured that they were just ordinary spiders. I'm not taking any chances though, I've shut the door and am leaving it for Mr X to investigate when he gets home!
Thanks again.