At the 1923 general election held on 6 December, Marley won his first seat in Parliament with a majority of 2,872 votes; unseating the sitting Unionist MP, John William Lorden.

He was born in Shotts, Lanarkshire, Scotland and moved to London in 1917 to take up a teaching post at St Dominic's Boys' School in Hampstead (1917–19).

[4][5][6] In April 1929, the African-American concert singer Paul Robeson was refused entry to a London hotel.

He wrote to Marley complaining about his treatment and the letter was made public, causing uproar in the UK and the US.

The matter led to a debate in Parliament later that year (October 1929) into racial discrimination by English hotels.