Complex sentence: Of the 669 children saved from the Holocaust through Winton's efforts, more than 370 have never been traced, and the BBC News suggested in 2015 that they may not know the full story of how they survived the war.
Split into simpler sentences: Of the 669 children saved from the Holocaust through Winton's efforts, more than 370 have never been traced. The BBC News suggested in 2015 that they may not know the full story of how they survived the war.