William was the son of Richard and Mary Marrack of Whitchurch, near Tavistock, Devon. He was baptised in Tavistock in August 1831, when father Richard (born Newlyn, Cornwall) was described as an Agent. By 1851, Richard was a Dealer in Timber. Mother Mary (nee Haye) was also from Cornwall.
In 1851 William was an Apprentice Surgeon in Bedford Square, Tavistock, in the Household of Surgeon William Northey.
He had moved to Barrel Street in Liskeard, Cornwall, by 1861, where his sister Mary was a visitor, and he had a General Servant and a Stable Boy. He was a Member of the Royal College of Surgeons by then.
He married Lydia Comyns (born in 1839 in Devon), in 1862 in Plymouth.
In 1861, Lydia was living with her mother Fanny, a Clergyman's Widow, in St Andrews, Plymouth.
Living still in Liskeard in 1871, he was described as a Member of the Royal College of Surgeons and Licentiate of the Society of Apothecaries. Lydia, daughters Edith (born in 1863) and Mary (born in 1864), a Cook and a Housemaid were in his household.
By the 1881 census in Liskeard he and Lydia had 4 children, Mary and Edith, plus sons George Comyns and Richard, all born in Liskeard, and 2 Servants.
In 1891 he was living, with Lydia, in Earlsland House in Bradninch, Tiverton. He was a Registered Surgeon, born Tavistock. They had two Domestic Servants.
William died, in Worthing, in December 1898, leaving his estate to his widow.
Between 1891 and 1898, the family must have moved to Heene as, in 1901, Lydia Marrack, widowed, aged 62, was living on her own means, with widowed daughter Mary Fanny Greet, Grandaughter Edith Greet, and two servants, in Holcombe House in Heene Road.
In the same year, Lydia's daughter Edith Comyns Marrack married Charles Young in Sussex.
In 1911 Lydia was living at 61 Portsmouth Road, Woolston, Hampshire, Head of the Household, with daughter Mary, and son George, a Surgeon, plus two General Servants.
Lydia died in 1913 in Woolston.
Holcombe House was an Hotel until the late 1980s, then a Rest and Retirement Home, before being demolished in 2004, to be replaced by 14 flats for people over 55.