Date of death, estimated year of birth of circa 1822 from age, from headstone in the "Church of the Holy Name Boyton" churchyard and found when Brian of nzolivers visited Devon and Cornwall in April 2008.

Date of birth was listed as 1818 from unconfirmed information (blue hand-written document of unknown source) collected by Brian Oliver of nzolivers.com (b.1950) on his April 2008 visit to Devon. However, working backwards from date of death on Francis’ headstone, he would of been born circa 1822? The date of 1822 also works out from the 1851 Census.

Dax Eric Clayton Lloyd born 25 April 1969, claims date of birth about 1821 in Holsworthy, Devon, England.

Sarah Ferguson (nee Churton) gives date of death about 1822 in Pyworthy, Devon, England. Sarah confirms date and place of marriage to Mary Parsons.
Sarah says in the 1851 Census, was living at Boyton, Devon, England. In the 1861 Census was living at Northcott, Devon, England.

Baptism of 8 April 1822 from Peter (Pete) G M Dale of Toronto, Ontario, Canada. Pete is related to the Olivers in Devon. Pete's great great great grandfather was John Batten (Battin) b. 1793, sister of Ruth Batten who married James Oliver b.1805. Ruth and James emigrated to New Zealand in 1841.

Entry found in July 2020 in 1851 England Census taken on the night of 30 March 1851 for Northcott Hamlet in Boyton Parish, County and Parliamentary division of Northern Division of Devon, for Boyton Mill
Francis Oliver, Head, Married, age 29 Miller, born Pyworthy, Devon, England [circa 1822]
Mary Oliver, Wife, Married, age 28, Boyton, Cornwall, England [circa 1823]
Ann Oliver, Daughter, Unmarr, age 7, Boyton, Cornwall, England [circa 1844]
William Oliver, Son, Unmarr , age 5, Boyton, Cornwall, England [circa 1846]
Francis Oliver, Son, Unmarr, age 3, Northcott Hamlet, Devon, England [circa 1848]
Matilda Oliver, Daughter, Unmarr, age, Northcott Hamlet, Devon, England [circa 1850]

From records online for Parish of Pyworthy in the county of Devon, as alerted by Katia and Tim Oliver In an email dated 4 January 2021. Tim Oliver is a x3 great grandson of James and Ruth Oliver, his grandfather being Ivor James Clark Oliver (1907-1989).
Name: Francis Oliver
Event Type: Baptism
Event Date: 08 Apr 1822
Event Place: Parish of Pyworthy in the county of Devon, England
Sex: Male
Father's Name: John Oliver
Mother's Name: Grace Oliver
Parent's Abode: Derril, Devon (Three-quarters of a mile north of Pyworthy)
Father's Trade or Profession: Farmer
From Scans of original parish registers from Cornwall [including Devonshire] containing baptisms from 1538 to 1910 published on FamilySearch:
https://familysearch.org/ark:/61903/1:1:Q2M3-32LL
Note: Login to FamilySearch required

Date and place of burial, and confirmation of other key dates and places, from a link received from Katia, wife of Tim Grant Oliver, in an email dated 14 January 2023:
Name: Francis Oliver
Birth: 1822, Pyworthy, Devon, England
Baptism: 8 Apr 1822, Pyworthy, Devon, England
Marriage: 20 August 1843, Boyton, Cornwall, England,
Death: 3 June 1897
Burial: 7 June 1897, Boyton, Cornwall, England

Tim Oliver is a x3 great grandson of James and Ruth Oliver, his grandfather being Ivor James Clark Oliver (1907-1989).

Brian of nzolivers responded to questions from Katia in the 14 January 2023 email, about the dates of ownership of Boyton Mill:
QUESTION: Who is the last one from the Oliver family living in Boyton Mill? Ann Yeo, Francis's daughter, and her husband Thomas Yeo? Or their son Francis Oliver Yeo? 

ANSWER: Please see page 4 of "Boyton Mill - a History”:
https://nzolivers.com/articlesdocs/BoytonMillHisto...ll_Pages/Image4.html
This paper reads that Francis inherited the Mill after his mother died in 1859 [actually was 1860]. After Francis' death in 1897 the property was acquired by Thomas Yeo.
[Was the husband for daughter Ann, Thomas Yeo?].

And, please see page 8 of the PDF, 5th paragraph:
https://nzolivers.com/articlesdocs/Deborah Laing-Trengrove Report.pdf
This reads, "The mill remained in the ownership of the Oliver family until 1897, followed by Thomas and then Frank Yeo, then Jack Cole the last person listed as miller, who sold the mill in 1951 to a Mr Hill who ‘modernised the premises’”.
[Was Frank Yeo the son of Ann (nee Oliver) and Thomas Yeo?].
[Need to research if Jack Cole is related. Katia wrote, The mother of John's (born 1802) wife, Mary, had a maiden name Cole].

Confirmation that daughter Ann Oliver is believed to have married Thomas Yeo in 1870 in Holsworthy, according to a follow-up email dated 20 January 2023 from Katia.

Also, Katia writes in this 20 January 2023 email, “All of Francis Oliver's children, except of Ann, died before him. Therefore, we believe Ann and Thomas Yeo inherit the Boyton Mills.
Ann and Thomas had a son Francis Oliver Yeo. Could he be called Frank?”.

Date of burial confirmed from a link to an image in an email dated 20 January 2023 received from Katia, wife of Tim Grant Oliver:
Burials in the Parish of Boyton in the County of Cornwall in the Year 1847
Name; Francis
Abode: Boyton Mill
When Buried: June 7 1897
Age: 75
By Whom the Ceremony was performed: Thomas Walters, Vicar [was Vicar 1870 to 1907]

Mill Ownership
Katia, in an email dated 5 March 2023, writes further about the ownership of the mill:
Based upon electoral rolls the following people lived in Boyton Mill -
1910 - 1915. Francis Yeo
1918 - John Martyn Cole and Ann Maker Cole
1919 - 1922. Ann Maker Cole and James Leslie Brown
1923 - 1928. Ann Maker Cole and William Thomas Cole.
1929 - 1930. Ann Maker Cole, Florence Gertrude Cole and William Thomas Cole.
So, it looks like Francis Yeo stopped living in Boyton Mill somewhere between 1915 to 1918.
John Martyn Cole and his wife Ann Maker Cole, started to manage Boyton Mills. Then John M. Cole died in 1918. Ann M. Cole became a miller and farmer. Initially, her brother James Leslie Brown helped her, who was  a waggoner  in 1911. In 1923, John M. Cole's brother William T. Cole started to help Ann M. Cole.
In the 1881 England Census, Francis Oliver had his nephew, John Oliver Walters, son of his sister Ann Walter (nee Oliver), as an indoor farm servant.
In the 1891 England Census, in the Cole household, John Cole, a carpenter, born in Tetcott, had two sons: John M. Cole, a Miller Assistant, possibly an assistant to Francis Oliver? And, William T. Cole, a carpenter.
In the 1911 England Census, John M. Cole was living in Northcott Hamlet and mentioned as a miller in his own account at ‘Great Mill’? 
The 1939 Register (collected by enumerators on the 29 September 1939 shortly after Britain declared war) shows Ann M. Cole was a miller and farmer. Her son Sidney was a working manager, farming and milling.
The burial document, which you shared with us, says:
1918 - John Martyn Cole died at age 47.
1942 - Ann Maker Cole died at age 67.
1946 - William Thomas Cole died at age 73.
Was the Cole family related to Olivers? Was John Martyn Cole, Francis Oliver's assistant? Or was he just a miller in the area...?

In an email reply to Katia on 19 March 2023, I wrote:
I still have not found any marriage connection between the Oliver family and the Cole family.
Yes, the 1881 England Census does list John Oliver Walters being Francis’ nephew although says an indoor farm servant. Was he working inside the Mill?
Yes, John Martyn Cole would have worked for Francis Oliver as per the 1891 England Census.
Regarding the 1911 England Census for John Martyn Cole, to my knowledge there was only one mill in the area and maybe he called it the Great Mill for some reason? His address is given Northcott Hamlet which is very very close, just up the hill from the Mill. And, he is working the Mill on his own account.
Now, when you look at the 1911 England Census for Francis Oliver Yeo (1870-1936), he was living at Boyton Mill but was by now only a ‘farmer’. So, he must of sold or leased the Mill operation to John Martyn Cole, who was living up the hill?