research on H2 antagonist. Residential Accommodation The Frythe site was closed by GlaxoSmithKline and sold to a property development company on 19 December 2010. In 2017 the conversion of the property into flats was still underway. References Buildings and structures in Welwyn Hatfield (district) Country houses in Hertfordshire Edward Blore buildings GSK plc Gothic Revival architecture in Hertfordshire Houses completed in 1846 Imperial Chemical Industries Military history of Hertfordshire Pharmaceutical industry in the United Kingdom Pharmaceutical research institutes Research institutes in Hertfordshire Special Operations Executive Locations in the history of espionage Unilever World War II sites in England