 However the BBC kept a number of such cameras in operation at BBC Television Centre, their various regional outposts and their BBC Elstree Centre for some years afterwards, the last being at Elstree until July 1991; they were kept running by "cannibalising" identical cameras left behind by Central when the BBC purchased Elstree from them in 1984 as well as BBC EMI 2001s disposed of in previous years.In 1963, prior to the development of the 2001, an experimental four tube camera was constructed by EMI engineers.This experimental camera had been inspired by RCA's new four tube camera, the TK-42, and used the same tube arrangement, i.e.