In 1867 he married Amelia Elizabeth Hyde of County Cork. They had no children. His wife was a campaigner for women's suffrage and a prominent public figure in her own right.
From 1880-85 he was member of parliament for Salford, Lancashire.
On the creation of the London County Council in 1889, Arnold was elected as a county alderman, and was chairman of the council from 1895 - 1897. He was knighted in 1895. He was also a Deputy Lieutenant and Justice of the Peace for the County of London.
He died at his home in Kensington in May 1902, aged 68.
Wikipedia page  and Wikisource page [https://en.wikisource.org/wiki/Arnold,_Arthur_(DNB12).
An article on Arnold Day 
Opening of Telegraph Hill 
- ↑ 1.0 1.1 1.2 Obituary: Sir Arthur Arnold, The Times, 21 May 1902, p.6
- ↑ 2.0 2.1 G. S. Woods, rev. Jonathan Spain (2004). Arnold, Sir (Robert) Arthur (1833–1902). Oxford Dictionary of National Biography. Oxford University Press. Retrieved on 2008-10-21.
- ↑ John Sutherland, The Stanford Companion to Victorian Fiction, Stanford University Press, 1989