He left school at 13 and found employment with Lever Brothers, later studying engineering part-time at Wellington Technical College.

He then gained a job at the New Zealand Railways Department in the late 1920s, where soon after his wages were cut by 10% as part of the retrenchment policies of the United–Reform coalition government.

At the outbreak of World War II his position with the railways was classified as a reserved occupation and he was ineligible to serve overseas.

[3] He then transitioned to national politics, representing the Wellington area electorates of Onslow from a 1954 by-election to 1963, then Porirua from 1963 to 1969, then Western Hutt from 1969 to 1975.

[5] In February 1954 long-serving Labour MP Harry Combs announced he would retire at the general election later that year owing to ill health.

May first learned of his default victory via a telegram from Petone MP Mick Moohan inviting him to attend that evening's session of parliament.

[9] After the formation of the Third Labour Government May stood for the cabinet and was tied for the final place in the caucus ballot with Ron Bailey (whom he had shared an office with for many years) with May narrowly winning.

Prime Minister Norman Kirk regretted two friends being pitted against one another but was relieved when Bailey took the defeat graciously.

[12] His main accomplishment as a minister was restructuring New Zealand's local government setup in 1974, largely inspired by the "May Report" over a decade earlier.

Nevertheless May pointed to the fact that in every previous election he had gained votes after specials were counted and stated "I am not throwing in the towel yet".

[17] His brother, Josiah Robert Philip May, was also a Petone Borough Councillor who had played rugby for Wellington B and had married Henry's wife Annie's sister Theresa Winifred McNeill.