Hello
Some of my ancestors are buried at St Mark's. Several years ago (5?) my brother and I went to have a look. There was no access, there was a fence all around. However we were able to squeeze through a hole in the fence.
It was very disappointing. We were lucky my ancestors grave was one of those remaining above ground, we spotted it after a fruitless half hour lookin looking at slabs laid down. If you are looking for one of those it would be very difficult, the slabs were covered in overgrowth and rubbish.
Someone on here posted a link to images of Lancashire and Cheshire parish registers. St Mark's were there. I think the link was to part of familysearch but I don't know how to get there.
Suds