Complex sentence: A leading supporter of John Kingsley Read, McCalden transferred his allegiance to the National Party soon after Read and other NF members founded the party in 1976 and became a leading contributor to the party journal "Britain First".
Split into simpler sentences: A leading supporter of John Kingsley Read, McCalden transferred his allegiance to the National Party soon after Read and other NF members founded the party in 1976. He became a leading contributor to the party journal "Britain First".