Arthur was born in Port Elizabeth, South Africa, the son of William Thomas Kingsmill, a merchant and his wife Helen Lavinia. He was baptised at St Mary's Church, Port Elizabeth on 20th December 1856. Arthur was educated in England and by 1874 was studying law at St John's College, Cambridge. He was admitted to the Inner Temple, London on 29th July 1876 and obtained a BA in 1879. He was called to the Bar in 1880. Arthur's mother died in 1882 and he returned to South Africa. He travelled constantly between South Africa and England over the years. On 24th April 1902, Arthur married Constance Barry by special licence in Cape Town. Their daughter Katherine was born in Pretoria on 14th July 1903. By 1905, the family had returned to England, living in Oxford Terrace, Paddington. A daughter Constance Helen was born in Richmond, Surrey on 19th June 1905. The family travelled out to South Africa the following year and a son Arthur was born in Pretoria on 28th November 1906. Gertrude was born in Port Elizabeth on 28th April 1908. Early next year, the family returned to England, living in Bournemouth where daughter Anne was born in 1910. By 1911, the family were in Worthing, living at "Constantia" in Grand Avenue. A son Richard was born on 1st November. By 1915, they were living at "Bramlyns" in Rowlands Road. Arthur died at "Caer Gwent" in Wykeham Road, Worthing on 19th June 1915. At the time of his death, Constance was expecting a child. The baby was born on 5th July and named Angela. Probate was registered in South Africa.
In November 1915, Constance took the family to South Africa. In April 1919, she married Lionel Burnand in Worthing. She died in Surrey in 1944.
Arthur's daughter Constance Helen May Spurrell is remembered on his stone. She was born in Richmond and baptised at St James church, Paddington on 22nd August 1905. She lived with her family in England and South Africa. In 1932, Constance married George Richard Spurrell a senior agricultural officer at Erpingham in Norfolk. The Spurrell family were an old Norfolk family, their home being Old Thurgarton Hall in Roughton. The couple sailed for Accra, Ghana on 25th January 1933. Constance returned to England the following year to give birth to her son Richard James Kingsmill Spuurrell in Hemel Hempstead. The family travelled to Ghana several times over the next few years for George's work. Constance died at the European Hospital, Kumasi, Ghana on 13th May 1939. Her death was registered in Cape Town. George married again at the end of the war. He died in Norfolk in 1986.