From Ducky McDuckface in the comments:
[Ross Clark in the Telegraph:] “While Oswald Mosley may have gained some traction in the 1930s, he never came remotely close to power.”
“Mosley then made a bold bid for political advancement within the Labour Party. He was close to Ramsay MacDonald and hoped for one of the great offices of state, but when Labour won the 1929 general election he was appointed only to the post of Chancellor of the Duchy of Lancaster, a position without Portfolio and outside the Cabinet. He was given responsibility for solving the unemployment problem, but found that his radical proposals were blocked either by his superior James Henry Thomas or by the Cabinet.
Mosley was always impatient and eventually put forward a whole scheme in the “Mosley Memorandum”, which called for high tariffs to protect British industries from international finance, for state nationalisation of main industries, and for a programme of public works to solve unemployment. However, it was rejected by the Cabinet, and in May 1930 Mosley resigned from his ministerial position. At the time, the weekly Liberal-leaning paper The Nation described his move: “The resignation of Sir Oswald Mosley is an event of capital importance in domestic politics… We feel that Sir Oswald has acted rightly — as he has certainly acted courageously — in declining to share any longer in the responsibility for inertia.” In October he attempted to persuade the Labour Party Conference to accept the Memorandum, but was defeated again. Thirty years later, in 1961, Richard Crossman described the memorandum: “… this brilliant memorandum was a whole generation ahead of Labour thinking.””