Complex sentence: The title was lost to the gauge Réseau Guerlédan in France in 1978 and regained from 1979, when the Réseau Guerlédan closed; however it was lost again in 1982, when the gauge Wells and Walsingham Light Railway opened.
Split into simpler sentences: The title was lost to the gauge Réseau Guerlédan in France in 1978 and regained in 1979 when that line closed. It was lost again in 1982 when the gauge Wells and Walsingham Light Railway opened.