Historically part of the West Riding of Yorkshire, Thornhill was absorbed into Dewsbury County Borough in 1910.A hoard of 27 Roman denarii found in Turnip Lane and pottery at the cross indicate a substantially earlier settlement.Some historians claim that the grave bearing the name Osbehrt is that of Osberht of Northumbria, who was killed on 21 March 867 while fighting the Viking Great Heathen Army led by Ivar the Boneless.The Celtic kingdom of Elmet that covered parts of modern West Yorkshire collapsed in AD 617.A royalist heroine after the siege of Sheffield Castle in 1644, Lady Anne Savile's troops under Capt Thomas Paulden (brother of William Paulden) defended the hall against the Parliamentary forces under Col Sir Thomas Fairfax in August 1648.The Old Rectory survived and was home to several vicars, notably John Michell,[7] who rose to international prominence by developing an understanding of earthquakes, then devised an experiment to accurately determine the mass of planet Earth, but perhaps most intriguingly, attracted Benjamin Franklin (founding father of the USA), Joseph Priestley, Jan Ingenhousz, John Smeaton and others to a scientific meeting and overnight stay in 1771.Historically Thornhill (St Michael) was a large ecclesiastical parish and township in the wapentake of Agbrigg, West Riding of Yorkshire which joined the Dewsbury Poor Law Union in 1837.Thornhill Community Academy, the area's secondary school had a GCSE pass rate of 84% in 2010, an increase of 22 percentage points from 2009.There are a number of local shops and off-licences in Thornhill and numerous takeaways ranging from traditional English to Italian cuisine.