Sir Arthur Robert Guinness, son of Frank Guinness, who arrived at Lyttelton by the ship Tory in August 1852. He was educated at Christ's College, Christchurch 1854–1859 (being no. 31 on the list). He received his legal education from Edward Harston and then from Garrick and Cowlishaw, before being admitted to the bar in 1867. ] He then practised as a barrister and solicitor in Greymouth, where he served on the Westland Provincial Council from 1874–1876,[ and was then a member of the Grey County Council from 1876–1890, including nine as its chair.

Member of Parliament
New Zealand Parliament
Years Term Electorate Party
1884–1887 9th Greymouth Independent
1887–1890 10th Greymouth Independent
1890–1893 11th Grey Liberal
1893–1896 12th Grey Liberal
1896–1899 13th Grey Liberal
1899–1902 14th Grey Liberal
1902–1905 15th Grey Liberal
1905–1908 16th Grey Liberal
1908–1911 17th Grey Liberal
1911–1913 18th Grey Liberal
Guinness first stood for two-member Grey Valley in the 1876 election and out of the four candidates, he came last. In his second attempt in 1884, he defeated the incumbent, Joseph Petrie, in the single-member electorate that was by now called Greymouth. He remained a member of the House of Representatives for Greymouth until 1890, and then represented the Grey electorate until his death in 1913. He belonged to the Liberal Party.

He was Chairman of Committees from 1893 to 1902 then the 7th Speaker of the House of Representatives from 1903 until his death in 1913. Upon the death of William Steward on 30 October 1912, he became Father of the House. When he died, his replacement from the Grey by-election was Paddy Webb, who was elected on the second ballot with Liberal support.