Subsequently, his father moved to Port Molyneux, near Balclutha where, at various times, he was chairman of the road board, school committee, and county council.

On leaving school in 1875, he was employed by Sparrow and Co., at the Dunedin Foundry, and served an apprenticeship of five years to boilermaking and iron shipbuilding.

[1] Jenkinson occupied rooms on the third floor of a building in The Octagon, Dunedin where a fire on 8 September 1879 killed thirteen people, and after narrowly escaping through the staircase, he returned upstairs with his roommate, where they found a woman and brought her out.

In 1886, he accepted employment in the Addington Railway Workshops, but left in the following year as a protest against the system of piecework, which was shortly afterwards abolished.

Jenkinson returned to the Addington Workshops in 1888, and took an active part in the formation of the Christchurch Boilermakers' Union, of which he was secretary for several years, and afterwards president and also treasurer.

He advocated and inaugurated scientific lectures under the auspices of the Union, and was successful in having the study of boilermaking promoted in the Canterbury School of Engineering.

Jenkinson assisted in forming the Amalgamated Society of Railway Servants, and was a delegate from the Canterbury branch, at the first conference.

[7] Jenkinson unsuccessfully contested the Clutha electorate for the Liberal Party in the 1914 general election against the incumbent, Alexander Malcolm.