Apparently the park on Station Road was not the Wesleyan Chapel site and graveyard, so the source of the headstones ranged around the park walls is a mystery to be solved during my visit to Holmfirth in the Autumn.
My copy of Ian Harlow's book
Holmfirth Floods: The Story of the Floods in Holmfirth arrived in today's mail. On page 29 in the section about the 1852 flood, he writes 'On the opposite side of the river to the Holmfirth Mill stood the old Wesleyan Chapel, built in 1810 and surrounded by a graveyard. The chapel was flooded to pew height, but the ministers and their families, living just a little higher up the slope, were just clear of danger. Several coffins were washed up from the graveyard. Of particular poignancy was the fate of Mr John Harpin; his vault was torn open and his coffin, his resting place for ten years, floated downstream with his remains. Ironically Mr Harpin was the owner of Harpin's Mill, Near Hinchliffe Mill, and was one of the chief promoters for the building of the Bilberry Reservoir.'
In another source that I can't track down at the moment, the 'Holmfirth Mill' mentioned above was called 'Town Mill', which was located on the present site of the Post Office. That can be pinpointed via the listing at
http://en.wikipedia.org/wiki/List_of_mills_in_Holmfirth#cite_note-NBR_63237-68 nearly at the bottom of the page in the listings for Wooldale. Click the coordinates, select your favorite version of your favorite mapping system and zoom in to see the detail around the pointer. So the Wesleyan Chapel on the opposite side of the river would have been approximately on the site of the present Methodist Church.
In my wanderings, I also happened upon this
http://www.amazon.co.uk/Antique-Inundation-Holmfirth-Remains-Wesleyan/dp/B00K53UQA6. If you click the image, hover over the center right picture and click, you'll see the flood 'scene opposite the Wesleyan Chapel'. That's the ruins of Town Mill.
Next I need to follow up in the summary of the 1851 census. The summaries usually list all the buildings in order, whether or not they're occupied, giving the use if it's other than a dwelling. That might tell me what, if anything, was on the site of the park in question.
Marianna