Original: The railway was formed by the amalgamation of several smaller railway companies, the largest of which were the London & South Western Railway (LSWR), the London, Brighton and South Coast Railway (LBSC), and the South Eastern and Chatham Railway (SECR).
Simplified: The railway was formed by the amalgamation of smaller companies, the largest of which were the London & South Western Railway, the London, Brighton and South Coast Railway, and the South Eastern and Chatham Railway.