<P> The gardens are not visible from Kensington High Street . </P> <P> Derry and Toms department store was opened in Kensington in 1933 . The gardens were laid out between 1936 and 1938 by Ralph Hancock, a landscape architect, on the instructions of Trevor Bowen (then vice-president of Barkers, the department store giant that owned the site and constructed the building). They cost £ 25,000 to create and visitors were charged 1 shilling to enter . Money raised was donated to local hospitals and £ 120,000 was raised during the next 30 years . </P> <P> The building housed the department store Derry and Toms until 1973, and then Biba until 1975 . Since the 1980s the garden has been used as a restaurant and club . </P> <P> The Roof Garden was listed as a Grade II site by English Heritage in 1998 . </P>

When did the roof gardens above kensington open to the public