Complex sentence: The series began as a feeder series to the European Drift Championship, however the partnership between the BDC and EDC organisers ended at the end of the season and the BDC became a professional series in its own right.
Split into simpler sentences: The series began as a feeder series to the European Drift Championship. However, the partnership between the BDC and EDC organisers ended at the end of the season and the BDC became a professional series in its own right.