Complex sentence: The Swanage Railway is a heritage railway and was a branch line from near Wareham, Dorset to Swanage; it opened in 1885, the independent company that built it being amalgamated with the larger London and South Western Railway in 1886.
Split into simpler sentences: The Swanage Railway is now a heritage railway, originally a branch line from near Wareham, Dorset to Swanage opened in 1885. The independent company which built it was amalgamated with the larger London and South Western Railway in 1886.