From those humble beginnings in the 18th century was to come the industrial base on which the growth and prosperity of Dartford were founded. In 1840 the mustard factory of Saunders & Harrison was described as being "perhaps the largest in the kingdom". Dartford Paper Mills were built in 1862, when excise duty on paper was abolished. Between 1844 and 1939 the fabric printing works of "Augustus Applegath" were in being in Bullace Lane: again a firm using the waters of the river. RAF Joyce Green, at Long Reach, near Dartford was one of the first Royal Flying Corp airfields, It was established in 1911 by Vickers Limited (the aircraft and weapons manufacturer, who used it as an airfield and testing ground. It was superseded by Biggin Hill, and closed in 1919. The demand created by World War I meant that output at the local Vickers factory multiplied, with a positive effect on the local economy. Burroughs-Wellcome chemical works (later incorporated into GlaxoSmithKline) made Dartford a centre for the pharmaceutical industry. There has been a large power station at Littlebrook on the Thames, to the north of the town, since 1939. The current station, which features one of the tallest chimneys in the UK, dates from about 1978.