Complex sentence: The transition to all-figure dialling occurred between 1966 and 1970 and was initiated by the General Post Office and was one of the first in a series of changes in the organisation of British telephone numbers.
Split into simpler sentences: The transition to all-figure dialling occurred between 1966 and 1970 and was initiated by the General Post Office. It was one of the first in a series of changes in the organisation of British telephone numbers.