Complex sentence: After a poor showing at the 1979 general election, internal factional division heightened within the NF, culminating in chairman John Tyndall leaving the party in 1980, and founding the New National Front (NNF), which became the BNP two years later.
Split into simpler sentences: After a poor showing at the 1979 general election, internal factional division heightened within the NF. This culminated in chairman John Tyndall leaving the party in 1980, and founding the New National Front (NNF), which became the BNP two years later.