According to family information, Mary Elizabeth Prebble was born on 9 May 1833 in Mersham, Kent, England, the youngest of six children of James Prebble, a carpenter, and his first wife, Ann Maria Gurr. Mary's mother died in 1837 and the following year her father married again. His second wife was a widow, Ann Whitehead, formerly Stone.
Mary Prebble and her family arrived in Wellington in 1840 on the Aurora. About 1846 she moved to Canterbury, where she worked as a servant. She was first employed by Joseph and James Greenwood, who farmed land at Pūrau and Motunau; then she worked for the Gebbie family, who lived near Port Lyttelton. She was paid £8 per annum. Mary Prebble developed skills in butter and cheese making, and also began farming in her own right. With John Gebbie's encouragement she acquired her first cow.
Mary Prebble met Andrew Dawson while they were both employed by the Greenwoods, and married him on 19 July 1852 at the temporary Anglican church, Lyttelton. Six sons and six daughters were born to the couple between 1853 and 1878. Mary and Andrew remained with the Gebbies until June 1853, and then established themselves on 50 acres at Port Levy. The following year, desiring more land, they joined Mary's brothers at Prebbleton. They built up a large dairy herd, and also ran sheep and a Clydesdale stud. In addition Mary earned large sums of money from her cheese and butter making.
By 1872 the Dawsons had acquired sufficient capital to buy their own property. It was apparently Mary who selected Seaview, the 1,460 acre estate they purchased at Waterton, near Longbeach. Although the land was mainly swamp and tussock to begin with, the Dawsons drained it and developed it 'into a most desirable property'. Seaview was an arable farm, with its own flour mill. Mary's chief contribution to its prosperity was her recognition of the value of trees to stabilise the land, and give shelter as well as beauty to a windswept plain. The estate was distinguished by blue gums, planted by Mary and the children. If, as Charles Dawson's obituary suggests, 'his young heart occasionally rebelled at this task…his mother constantly encouraged him by saying that he would live to see the trees grow into a big and highly valuable shelter plantation'. Many of the trees still stand today.
Just as the Gebbies and her family had helped her, Mary Dawson helped both relatives and neighbours and was remembered as having 'a very generous disposition'. All but two of the children were established on farms in the Waterton area, and invaluable practical assistance was given to Mary's nephew, William Prebble, who expressed affection and admiration for Auntie and Uncle Dawson in his diary of the 1870s. Mary Dawson also cared for her frail half-brother, John Aurora Prebble, during most of his adult life. Her abilities as a nurse were much appreciated by the local community; she 'proved herself a wonderful aid to the sick'. Like Andrew, she was also an active member of the Anglican church.
Mary Dawson died at Waterton on 22 February 1924. She was of working class origins and apparently never learned to write; yet with her husband she built up an estate valued at nearly £25,000 in 1909. Resourceful and assertive, she was able to forge a life for herself and her family that she could not have hoped for in England.