After his father's death, the Hendersons moved to Newcastle upon Tyne in the North-East of England, where Agnes later married Robert Heath.

After finishing his apprenticeship there aged seventeen, he moved to Southampton for a year and then returned to work as an iron moulder (a type of foundryman) in Newcastle upon Tyne.

In 1892, Henderson entered the complex world of trade union politics when he was elected as a paid organiser for the Friendly Society of Iron Founders.

In 1900 Henderson was one of the 129 trade union and socialist delegates who passed Keir Hardie's motion to create the Labour Representation Committee (LRC).

[4][5] The Labour National Executive Committee had rejected the Second International's request for a meeting of European socialist parties on the war in Stockholm, but after Henderson convinced it to give provisional support after visiting the Russian Republic as an envoy and recognizing that the Russian Provisional Government would collapse if the war continued.

[6] In August 1917, three months before the Balfour Declaration, the Labour Party issued a statement in support of a Jewish state in Palestine.

It proclaimed a socialist party whose principles included a guaranteed minimum standard of living for everyone, nationalisation of industry, and heavy taxation of large incomes and of wealth.

[8] Henderson lost his seat in the "Coupon Election" of 14 December 1918, which had been announced within twenty-four hours of the end of hostilities and which resulted in a landslide victory for a coalition formed by Lloyd George.

In a letter to the Soviet Commissar for Foreign Affairs, Georgy Chicherin, written on 10 February 1922 and referring to the Genoa Conference, Lenin wrote: "Henderson is as stupid as Kerensky, and for this reason he is helping us.

Diplomatic relations were re-established with the Soviet Union and Henderson guaranteed Britain's full support to the League of Nations.

The Cabinet agreed that it was essential to maintain the Gold Standard and that the Budget needed to be balanced, but were divided over reducing unemployment benefits by 10%.

At first, Henderson gave strong support to Prime Minister MacDonald throughout the financial and political crisis of August.

King George V implored MacDonald to remain and form an all-party National Government that would make the budget cuts.

Against his inclinations, Henderson accepted the leadership of the main Labour Party and led it into the general election on 27 October against the cross-party National coalition.

Henderson's Nobel Prize medal was stolen in a burglary of the office of the Lord Mayor of Newcastle on 3 April 2013.

All three of Henderson's sons saw military service during the Great War, the eldest, David, being killed in action in 1916 whilst serving as a Captain with the Middlesex Regiment (Duke of Cambridge's Own).