sentences:  The GPO largely did this to protect their success in the export market, but it actually had the effect of ultimately destroying it.This allowed competitors to develop their own improved switching systems ahead of the GPO.In 1960 the situation rapidly changed when the Australian Postmaster-General's Department rejected a system from a consortium of British manufacturers who offered a register-controlled version of a motor-uniselector system in favour of a crossbar system from the Ericsson.