The Skelmanthorpe flag is a banner symbolising political struggle that was made in Skelmanthorpe, a village near Huddersfield in Yorkshire in 1819. The banner was made to honour the victims of the Peterloo Massacre,Cavalry charge on 16 August 1819 into a crowd of 60,000–80,000 that had gathered at St Peter's Field, Manchester, England to demand the reform of parliamentary representation who were attacked during a peaceful demonstration at St Peter’s Fields in Manchester. It may have been made in Radcliffe Street, Skelmanthorpe by a Mr Bird. It is made of white cotton, 5 feet high and 5 feet 8 inches wide, with an embroidered border. It is divided into four quarters. One panel shows a bound man depicting a slave in chains, a symbol of the Society for the Abolition of the Slave Trade, and a single eye, the eye of God, keeping watch over humankind, a symbol of justice.
The banner was made at a time when social changes caused by industrialisation and urbanisatation had led to demands from the working and middle classes for electoral reform and especially commemorates the Peterloo Massacre in August 1819. The flag was one of thousands of banners carried at reform meetings when it was mounted between two poles to accompany the contingent from Skelmanthorpe. It was carried to a reform meeting at Almondbury Bank in November 1819, and to other meetings including the Chartist rally attended by 250,000 people at Peep Green between Roberttown and Hartshead in 1837. The banner was hidden between meetings, buried in a special box to prevent its destruction and the arrest of its custodion by the authorities. In 1884 it was paraded at a reform meeting in St George’s Square in Huddersfield. It was found folded up in a disused warehouse by Fred Lawton, in Skelmanthorpe and given to Huddersfield’s Tolson Museum in 1924.