Complex sentence: From 1 June 1878, the GNR ran six trains a day to and from 1 August 1880 the SER ran services to and on behalf on the GNR.
Split into simpler sentences: From 1 June 1878, the GNR ran six trains a day to. Using this link the SER ran services from 1 August 1880 to and on behalf on the GNR.