In 1834, Jacob Unwin founded the Gresham Steam Press, later the Unwin Paper Press, in Mansion House in the City of London. His sons, George and Edward, moved the Unwin Paper Press in 1871 to the river Tillingbourne near Chilworth. They enlarged an existing paper mill and named the new mills the Gresham Paper Mills.
John Ruskin wrote to the Unwin brothers to congratulate them on moving their business from London to the impoverished countryside and for their decision to use water to power the paper mill.
The mill thrived. It was a major employer for many workers who walked each day from local villages such as Shalford, Blackheath and Albury and beyond. The railway line that was built in 1849 linked Chilworth to the London line and was vital to the paper mill's success. It brought workers from more distant towns and villages, raw materials to Chilworth from London and took finished goods back.
After the fire of 1895, George Unwin wanted not only to rebuild the mills but also to develop and modernising them. The landowner, the Duke of Northumberland, withheld his permission for these plans, requiring the mills to be rebuilt in their exact original form. Unable to reach agreement, the Unwins moved the Gresham Paper Mills in 1896 to a new site just outside Woking.
As the construction of the new Greshambury Institute was underway, Unwin came to an agreement with the Church to buy the building. When the firm moved to Woking, the new building was taken over by the church and the Parish of Shalford and became the new church of St Thomas.