The Coal Mines Act 1930 (20 & 21 Geo. 5. c. 34) was an act of Parliament which introduced a system of quotas in the coal mining industry of Great Britain. It was a major achievement of the Labour Party, which revoked the eight hour day that had been enacted in 1926, replacing it with a 7 1/2 hour day. Mine owners were allowed to fix quotas and minimum prices. Theoretically, the new commission was to plan to close less-efficient pits, but it was not effective. Historian A. J. P. Taylor says that: