Thank you Osprey.
I earlier had not found that 1792 burial at Madron and thought that Mary (Gidley) may have been the one who was buried at St Erme in 1811 (no husband shown but aged 87 - born 1724) as St Erme was where her husband, William Gidley, was baptised on 1 Sep 1718. The 1792 burial looks more promising and I will follow it up. William Gidley was buried at Madron on 15 Sep 1803 (age 85). I do not have a copy of his will and will try to find a copy.
Mary's children were Mary 1751, Jane 1753 and Honor 1755 (all baptised at Sancreed) and William 1757, Richard 1759 and Nicholas 1761 (all baptised at Madron) and so I supected that Mary may have been baptised at St Columb Minor on 3 Feb 1721 (parents Nicholas and Mary) as she had siblings called Richard 1726, Honor 1729 and Nicholas 1733.
However, St Columb Minor is some distance from Madron and I have seen another tree showing that the 1721 Mary George (parents Nicholas and Mary) married in 1747 to George Woolcock. Another Mary George (parents Richard and Mary) was baptised at St Columb Minor on 15 Aug 1719.
Finally, another Mary George was baptised 1 Jan 1724 in Madon/ Penzance but none of the names of that Mary's parents nor siblings appeared as the names of William's and Mary's children so I have doubts that that 1724 Mary was the one I was looking for.