Main Line to The South - Part 3: Swaythling, St.Denys, Northam, Southampton Terminus and Southampton CentralMain Line to The South Part 3: Swaythling, St. Denys, Northam, Southampton Terminus and Southampton Central 34. 95 The London and Southampton Railway opened its line in 1840, the first major railway in the south of England soon to become the London & South Western Railway and eventually in 1923 the Southern Railway. Part 1 was concerned with the line from Basingstoke to Winchester. Continuing our journey, Part Two describes the line through to