Thanks.
I got most of the marks off at weekend, but there was one stubborn patch. Unfortunately I chose the wrong product to tackle it and it looks like I've taken the colour out of the marble - you can see where the product has run down
I've just been reading that it can be 'polished out' by a professional using a buffer and automotive polish. My son is a body shop technician and uses a buffer in his work. Am I naive in thinking that he may be able to restore the lustre?