Complex sentence: To celebrate the 150 year anniversary a cavalcade was held between Shildon and Heighington on 31 August 1975 with a replica of "Locomotion" heading a procession completed by the prototype high-speed train.
Split into simpler sentences: To celebrate the 150 year anniversary a cavalcade was held between Shildon and Heighington on 31 August 1975. A replica of "Locomotion" headed the procession that ended with the prototype high-speed train.