William Strutt was a pioneer in the construction of fire-proofed textile mills. Belper's original North Mill was completed in 1784, but burnt down in 1803. To help prevent this happening again, Strutt rebuilt the mill, which opened in 1804, with the basis of a framework of cast-iron columns with additional elements of fire-proofing between the floors. The 'flower-pots' were used because they are extremely fire-resistant, extremely light and extremely strong, due to their circular profile. The pots were probably manufactured at local brickworks owned by the Strutts. When other mills in the Belper and Milford complex were demolished in the 1960s, members of Belper Historical Society had the foresight to rescue a sample of the pots.