As a rugby player, Arnold played at club level for Morriston, Llanelli, Swansea, Neath, London Welsh, Leicester and Glamorgan.

Arnold played two games for Leicester Tigers on their tour to Devon in 1902.

Arnold was picked for Glamorgan in its match against New Zealand in December 1905 and he also played for Llanelli against South Africa in 1906 and was part of the Llanelli team that beat the 1908 touring Australian team.

By profession, Arnold was an architect and surveyor in Morriston and Swansea and surrounding areas.

Arnold was elected as a Professional Associate of the Surveyors Institution in October 1907 and became a Fellow of the Surveyors Institution (FSI) in June 1919 - although he was already described as FSI e.g. when reported as a candidate for election as borough estate agent and valuer (Swansea) in The Cambria Daily Leader.