Complex sentence: Since 1969 he had worked for the Confederation of Health Service Employees, first as assistant regional secretary, then from 1970 to 1974 as regional secretary for Yorkshire and East Midlands.
Split into simpler sentences: Since 1969 he worked for the Confederation of Health Service Employees. First as assistant regional secretary, then from 1970 to 1974 as regional secretary for Yorkshire and East Midlands.