“The phrase “dark Satanic Mills”, which entered the English language from this poem, is often interpreted as referring to the early Industrial Revolution and its destruction of nature and human relationships.

This view has been linked to the fate of the Albion Flour Mills, which was the first major factory in London. Designed by John Rennie and Samuel Wyatt, it was built on land purchased by Wyatt in Southwark. This rotary steam-powered flour mill by Matthew Boulton and James Watt used grinding gears by Rennie to produce 6000 bushels of flour per week.

The factory could have driven independent traditional millers out of business, but it was destroyed in 1791 by fire, perhaps deliberately. London’s independent millers celebrated with placards reading, “Success to the mills of ALBION but no Albion Mills.” Opponents referred to the factory as satanic, and accused its owners of adulterating flour and using cheap imports at the expense of British producers. A contemporary illustration of the fire shows a devil squatting on the building. The mills were a short distance from Blake’s home.”

From Wikipedia (I admit it, I love Wikipedia): http://en.wikipedia.org/wiki/And_did_those_feet_in_ancient_time