His mother died in 1914 during his first year at the Wanganui Collegiate School, and his father left soon after to serve in World War I.

[4] Porritt represented New Zealand at the 1924 Summer Olympics in Paris, France,[5] where he won a bronze medal in the 100 metre dash;[1] the winner was Harold Abrahams (1899–1978).

The race was later immortalised in the film Chariots of Fire, but due to Porritt's modesty his name was changed to "Tom Watson".

[1] Porritt is only one of two people to have the rare honour of twice being the New Zealand flag bearer at Olympic Games, the other being Les Mills.

[7] After retirement from athletics, Porritt was New Zealand's team manager at the 1934 British Empire Games in London and 1936 Summer Olympics in Berlin.

[3] He served in France until the evacuation from Dunkirk, then in Egypt, operating on seriously wounded soldiers from the North African campaign, and later landing in Normandy on D-Day.

[6] In 1955 Porritt was called to Eastbourne by the suspected serial killer John Bodkin Adams, to operate on his patient Jack Hullett for colon cancer.

[6][21] When he was elevated to be a Life Peer on 5 February 1973, he chose to honour his home town and was created Baron Porritt, of Wanganui in New Zealand and of Hampstead in Greater London.

"[23] Prior to the 1969 general election in September of that year, Porritt sparked a heated debate with a Labour candidate Eddie Isbey when he argued in a speech to the Southern Cross Medical Care Society that the welfare state was "uneconomic".

[24] Later, Porritt's wife also created controversy, when she replied to a question on equal pay for women by stating: "Perhaps when New Zealand, like India and Israel, produces a woman prime minister it will be time to call a halt to the emancipation movement".

[24] At his last Waitangi Day speech in 1972, Porritt caused more controversy by stating that: "Maori-Pakeha relationships are being dealt with adequately through the biological process of intermarriage.