Anthracite coal fields always suffer from blow out, and on the 10th of November 1907, one occurred which killed 5 men. In 1923, there were 607 men working at Seven Sisters, producing from the Furnace Four Feet, Brass and Nine Feet Big Vein seams. During World War 2 the colliery featured in an anti-Nazi film The Silent Village, made with the cooperation of the South Wales Miners Federation.
During the 1950s geological problems and changing economic conditions took their toll, and in May 1963 the colliery closed and the pit filled in. The men who had been employed at the Seven Sisters were transferred to the nearby Blaenant Colliery, which closed in 1990.