The Kingwell or Kingwill family
Henry Kingwill, the son of John and Ann, was baptised at Ashburton in July 1779. This fits with the age of the Henry Kingwill who died in 1851, aged 72.
Parish records
Henry and Elizabeth Kingwell, sometimes written as Kingwill, had various children baptized in Ashburton between 1813 and 1829. It seems likely that Elizabeth was née Mann, as this name was used as a middle name for one of their children: if this is the case, the couple had married in April 1807, when Elizabeth was a sojourner in the parish.
There do not appear to be records of any children of the couple baptised between 1807 and 1813, which seems unlikely as they had at least 8 children between 1813 and 1829.
Sometimes Henry's occupation was recorded as a carrier, sometimes as a husbandman. The surname also varies, sometimes recorded as Kingwell, and sometimes as Kingwill:
Henry Kingwill, baptized in July 1813. On this record Henry Snr's occupation was labourer.
Elizabeth Kingwill, baptized in April 1815.
Susan Kingwill, baptized in August 1817.
Mary Ann Kingwill, baptized in July 1819.
John Mann Kingwell, born and baptized in January 1822
Eliza Kingwill, baptized in April 1824.
Isabella, baptised on May 15th, 1826
Emma Kingwill, baptized in October 1829. She was buried at Ashburton in September 1833, aged 4.
Parish records

Henry [Snr.] and Elizabeth were in East Street for the 1841 census, with Mary Ann, John, Eliza and Isabella. Henry, a carrier, was approximately 60 years old, and Elizabeth 55.
1841 census HO107, piece no. 253, folio 8, p8

Henry Kingwill Snr. was buried in Ashburton in March 1851.
A memorial in the churchyard reads: 'Sacred to the memory of Henry Kingwell who departed this life March 6th 1851, aged 72 years also Elizabeth his wife who departed this life November 12th 1864 aged 79 years and of Eliza their daughter who died November 14th 1857 aged 33 years'
Parish records
Memorial in Ashburton churchyard.

By 1851 Elizabeth was a widow, still living in East Street. Aged 65, she was a proprietor of houses; she had been born in Ilsington. With her on census night was her unmarried daughter Eliza, a schoolmistress, and a one year old granddaughter, Isabella.
It seems likely that one year old Isabella was baptised as Isabella Kingwell Allen, the daughter of Charles Allen and Mary Ann. She was baptised in the parish of St John and St George, Exeter, in January 1850. Charles was a cabinet maker.
1851 census HO107, piece no. 1871, folio 263, p8
Exeter parish records

Henry Kingwill [Jnr.], a bachelor, married Jane Mugridge on May 21st, 1839. Henry, a carrier from East Street, was the son of Henry, also a carrier. Jane, from North Street, was the daughter of Thomas Mugridge, a grocer.
Parish records

The following month 'Kingwell, the Ashburton carrier' was called to testify to the character of John Edgecumbe, who was accused of stealing silver coins from an Exeter bank. Mr Kingwell said that he was a native of Ashburton, and that his father had also been a carrier to both Exeter and Plymouth. He had been living in London until very recently, and couldn't comment on the prisoner.
Western Times 22 June 1839, p4 col2

Henry and Jane were in North Street at the time of the 1841 census
1841 census HO107, piece no 253, folio 14, p22

In July 1847 Henry Kingwell was advertising 'A common stage carrying business' for sale by private contract. A horse, a light spring waggon and a two-horse waggon could be included in the sale if desired. The business had been carried on for over 40 years, but Mr Kingwell was disposing of it because of ill health .
Western Times 3 July 1847, p2 col2

Henry died two months later, and was buried in September 1847. He was 34.
Parish records

In May 1842 John Mann Kingwill sailed from Plymouth for Quebec (on board the Priscellia ?), and wrote back to his parents in Ashburton.
See Beyond Ashburton for more on the letter John Mann Kingwill wrote

John Symes probably married Elizabeth Kingwill in the Bermondsey registration district in the December quarter of 1850

The 1851 census found Isabella in Northfleet, North Aylesford, Kent, with her married sister, Elizabeth Symons. Both sisters had been born in Ashburton - Elizabeth was a schoolmistress; 24 year old Isabella was a dressmaker.
1851 census HO107, piece no 1609, folio 116, p15

Phillip Mugridge married Isabella Kingwell 21st April 1856 at St Pancras, London. They emigrated the following year.
Many thanks to Graham Jensen for this information.
See The Mugridge family for more on the Mugridges.

In 1861 John and Elizabeth Symes were living in The Strand, Westminster, London.
36 year old John was a messenger; his wife had no occupation. Elizabeth was born in Ashburton.
1861 census RG09, piece no. 179, folio 84, p2

On the 20th March 1865 Letters of Administration were granted with regard to the estate of Elizabeth Kingwill of Ashburton, who died on the 12th November 1864. They were granted to Elizabeth Symes, the wife of John Symes, Lodging-house keeper of 35 Bernard Street, Russell Square, Middlesex, daughter and one of the next of kin of Elizabeth. The value of the effects was under £200.
England and Wales Government Probate Death Index 1858-2019

In May 1868 John Symes, of 35 Bernard Street, Russell Square, Middlesex, a Lodging Housekeeper, and his wife Elizabeth, born Elizabeth Kingwell, assigned a life assurance policy to Stephen Yolland of Ashburton. The policy was for £100 - Stephen Yolland paid £10 for it.
Ref PEARSE/Box/1/6 and PEARSE/Box/1/8 South West Heritage Centre,