The British Rail Class 442 Wessex Electric ( or 5WES ) electrical multiple units , were introduced in 1988 on the South Western Main Line from London Waterloo to Southampton Central , Bournemouth , Poole and Weymouth . The British Rail Class 442 Wessex Electric ( or 5WES ) electrical multiple units were introduced in 1988 on the South Western Main Line from London Waterloo to Southampton Central , Bournemouth , Poole and Weymouth .