Hi Richard,
I haven't been to the churchyard yet, but I have been to the library, and found a booklet of memorial inscriptions for St Michaels done by Lancaster & District FHS (a different group to the group with the website).
Your Jonathan wasn't on any of the inscriptions listed unfortunately, but here are names and dates of other Harrisons in the churchyard, in case they are of interest. Not the exact wording, I just wrote down the names, places and dates:
Section A, row 1, grave 6
Ellen wife of Richard, d. 16 Apr 1815 in her 25th year
Richard Harrison of Overton, d. 22 Mar 1865 in 74th year
James Lamb, son in law, of Glasson Dock, d. 13 Mar 1882 age 67
Section B row 16
Adam Edward son of John & Margaret Harrison of Batty Hill, d. 26 Jan 1862 age 7 months
John Harrison d. 17 Nov 1867 age 48
Margaret, d. 26 Oct 1910 in her 80th year
Section E row 2 grave 7 with iron rail surrounding
James son of James & Ann Harrison of Cockerham d. 15 Aug 1820 in 4th year of his age
Ann sister of above d. 15 Aug 1845 age 29
Ann mother of above, d. 28 Jun 1846 age 59
Alice daughter of above [Ann] d. 31 Oct 1849 age 26
Richard Harrison of Liverpool, son and brother of above d. 11 Mar 1862 age 48
James of Batty Hill, husband & father of above, d. 27 Aug 1862 age 81
Section F row 12 grave 1
Annie wife of John Harrison of Sand Villa, 21 jul 1854 - 1 Jul 1896
John d. 25 Jul 1929 age 72
Annie wife of John d. 28 Aug 1936 age 68
Inside the church on wall plaques:
Harold Harrison, NZFA died of wounds Ypres 28 Oct 1917
Gerald J C Harrison, NZEF killed in action Polderhoek 3 Dec 1917 age 22
sons of James Harrison, New Zealand
Charles Geoffrey Harrison, Lieut, Yorks and Lancashire Regiment, k.i.a. Boulon 27 Nov 1917, son of Thomas Harrison, Kaikoura New Zealand
Grandsons of John Harrison of Cockerham
Wall plaque:
electric lighting for the church donated in memory of
James Harrison
Jane Harrison
and other names
there were one or two 20th century Harrisons as well, 1950s and 1990s.
Still very happy to go to the churchyard if any of these inscriptions are of interest. Batty Hill Farm and Sand Villa are still standing today (although google street view have the locations slightly wrong)
Barbara