Both sites have subsequently been redeveloped with no evidence now remaining of the entrance gates through which the horse and cart were frequently driven. The pilot episode and the first four series, which aired in 1962–1965, were recorded in the BBC Lime Grove Studios in London. When the show returned in 1970 after a four-year hiatus, the programme was made in the BBC Television Centre studios in west London, as from 1970 the show was recorded in colour. During its production in the 1960s and 1970s, "Steptoe and Son" marked itself out as radical compared to most UK sitcoms. This was an age when the predominant sources of laughter in British comedy were farce, coincidence, slapstick and innuendo. However "Steptoe and Son" brought greater social realism. Its characters were not only working class but demonstrably poor. The earthy language and slang used were in marked contrast to the refined voices heard on most television of the time: e.g., in "Back in Fashion", Harold warns Albert that when the models arrive, "if you feels like a D'Oyly Carte (rhyming slang for 'fart'), you goes outside." Social issues and debates were routinely portrayed, woven into the humour. The programme did not abandon the more traditional sources of comedy but used them in small doses. The characters, and their intense and difficult relationship, displayed deeper qualities of writing and performance than comedy fans were used to. "Steptoe and Son" is unique among 1960s BBC television programmes in that every episode has survived, despite the mass wiping of BBC archive holdings between 1967 and 1978. However, all the instalments from the first 1970 series and all but two from the second that were originally made in colour only survive in the form of black and white domestic videotape recordings. Copies were made from the master tapes for the writers by an engineer at the BBC using a Shibaden SV-700 half-inch reel-to-reel video recorder—a forerunner of the video cassette recorder. In 2008, the first reel of a black and white telerecording of the Series 5 episode "A Winter's Tale" (lasting approximately 15 minutes) was returned to the BBC; this is the only telerecording of a colour "Steptoe and Son" episode known to still exist. The original 2" Quad videotapes of all the episodes of the original 1962–65 series were wiped in the late-1960s. However, these episodes mostly survive on film transfers of the original videotapes as 16mm black and white telerecordings.