 The network has been modified several times through franchise reviews that have taken place in 1963, 1967, 1974, 1980 and 1991, during which broadcast regions have changed and service operators have been replaced.Only one service operator has ever been declared bankrupt, WWN in 1963, with all other operators leaving the network as a result of a franchise review.Separate weekend franchises were removed in 1968 (with the exception of London) and over the years more services were added; these included a national breakfast franchise from 1983 onward—operating between 6