The story
When the London and Southampton Railway was being constructed, it was realised that new business would be generated, and the dock facilities at Southampton needed to be extended. The Southampton Docks Company was created for that purpose in May 1836, with capital of £350,000. The area chosen was the town beach, at the confluence of the rivers Test and Itchen.
Over the following two decades there was a constant process of building larger and deeper facilities as vessels in use were larger, more numerous, and in need of additional repair facilities. By 1858 £706,000 had been spent.
In 1873 a further extension of the quay southwards down the river Itchen was undertaken, culminating in the formation of the Empress Dock between 1886 and 1890. The dock company was unable to raise the finance for the work, and obtained a loan of £250,000 from the London and South Western Railway. Southampton was able to take the largest vessels afloat at any state of the tide.
From Wikipedia’s article on London and South Western Railway, shared under CC BY-SA 4.0.3
