Archaeology find?

This is the third of these I've found this past year.  All on the moorland boundary wall at Howdale.  I thought it was a 'cup-marked-stone', maybe four or five thousand year old. These stones are common enough in the UK, Ireland and elsewhere.

However the archeologist from our national park thought that it was a stone which was used at the base of a base stone socket for a door to swing on - a heel stone. These too were once common in farms/houses and I've even heard of discarded circular grind stones being used for them too in Ireland. I don't think this example was ever been used as the inside was perfectly unworn. It's now recorded and back in the wall it came from.  (Howdale).  There was a very old and partially blocked field entrance in the location where I found it.  These were used before gates were hung using hinges were fixed to stooks using lead.

And here is a cup marked stone.  This one is also from the same wall at Howdale.

There were some archeologists working on Brow Moor, so I took this picture and one of them confirmed it was a cupmarked stone.

This one is back in the wall too.

(The coin is a 50p )

(right)  On the right hand side of this lintel over the sheep creep is a cup and ring marked stone.  Its in the same stretch of wall as the above two examples.  Although I rebuilt this length of wall the same year (2012) as I found these other stones, I only noticed the marks this during the summer this year  when passing by.  (grid ref NZ955016)