Coming from a very working-class background, the generosity of a family friend made it possible for him to get a start in life and train as a teacher; he entered politics through Poplar Borough Council, and was elected to Parliament to replace George Lansbury.

One of the lodgers was a young chemist, who decided to take responsibility for helping him develop his talent, and provided enough funds for Key to continue his education at the Mile End Pupil Teachers' Centre and to get practical training at a school in South Hackney.

Poplar's high spending to help the poor led to ever-rising rates, which became an extra burden on local householders.

In this situation, in 1921, the Poplar Labour councillors decided to act to relieve the burden and to make a political protest by refusing to collect the rates on behalf of the London County Council and other Metropolitan bodies.

Key himself, as Chairman of the Public Health Committee, moved a resolution to refer the estimates back to delete the contribution to the LCC.

To enforce payment, the LCC and Metropolitan Asylums Board issued writs against 30 Poplar councillors and Aldermen; however, somewhat inexplicably, Key was not among those proceeded against.

Poplar held out on other causes, including a minimum wage for its workers of £4 per week; this policy was ruled unlawful by the House of Lords in 1925.

In February 1947, Key was promoted to be Minister of Works, where he had to deal with the rebuilding of the House of Commons chamber and settling the layout of the Festival of Britain.

He remained a backbench MP although his attendance and frequency of speeches declined; in 1963 he was one of the MPs highlighted by the television programme That Was the Week That Was for not having spoken at all in the Chamber since the 1959 general election.