Complex sentence: It was started as the facilitator of the Blues Ski Races between the University of Oxford and the University of Cambridge in 1920; at this time it was almost exclusively attended by the racers and their families, when skiing was an expensive sport.
Split into simpler sentences: It was started as the facilitator of the Blues Ski Races between the University of Oxford and the University of Cambridge around 85 years ago. At this time it was almost exclusively attended by the racers and their families, when skiing was an expensive sport.