The Frythe is a country house set in its own grounds in rural Hertfordshire, just outside the village of Welwyn, about 30 miles north of London.
The Frythe was part of the property of Holywell Priory, Shoreditch, and in 1523 William Wilshere obtained a sixty-year lease of the Frythe from the priory. As a result of the dissolution of the monasteries, in 1539 the property was granted to Sir John Gostwick and Joan his wife. Within ten years, Wilshere had purchased The Frythe from Gostwick's heirs, and the property remained in the possession of the Wilshere family for several centuries.
The present "Gothic revival" mansion was built in 1846 for William Wilshere (MP for Great Yarmouth from 1837 to 1846). The architects were Thomas Smith and Edward Blore. After William Wilshere's death in 1867 the house was enlarged by his brother Charles Willes Wilshere who inherited it. In 1908 on Charles Wilshere's death, it passed on to his three unmarried daughters until the last one died in 1934. The estate passed to a great-nephew, Captain Gerald Maunsell Gamul Farmer who ran the house as "The Frythe Residential and Private Hotel".
'The Frythe' was commandeered in August 1939 by the British Military Intelligence. During World War II it became a secret British Special Operations Executive factory known as Station IX making commando equipment. Secret research included military vehicles and equipment, explosives and technical sabotage, camouflage, biological and chemical warfare. In the grounds of the Frythe small cabins and barracks functioned as laboratories and workshops.
The Frythe was for many years a commercial research facility, operated by Unilever and later GlaxoSmithKline. The Frythe site was closed by GlaxoSmithKline and sold to a property development company on 19 December 2010. The site is now standing empty while planning permission for houses is being applied for.