From Annals of Dover:
The building of the Admiralty Pier, which was intended, when commenced, to form part of the entire enclosure of the Bay, was preceded by three Inquiries - a Royal Commission in 1840, a Committee of the House of Commons in 1844, and Admiral Sir Byam Martin's Commission in 1845, which recommended that a harbour should be constructed in Dover Bay, with an area of 520 acres, at an estimated cost of £2,500,000. The works were commenced at Cheesman's Head, the point where a projecting arm would give most protection to the Bay; and, as the ardour of Parliament cooled down when about one quarter of the entire work was completed, it was very fortunate that the first operations were begun on that side, for that noble pier as a separate work has been of enormous public advantage for half a century. Eight different reports and plans were sent in by eminent engineers, and the plan of Mr. James Walker (then the Dover Harbour Engineer) was finally approved. The preparatory work was commenced in November, 1847, but the actual commencement of the building on the bed of the sea was on the 3rd April, 1848, without any public ceremony.
The first portion of 800 feet, starting from Cheesman's Head, on the western side of the Bay, was estimated to cost £245,000. It extended almost at right angles from the shore, facing the most exposed quarter from the south-west, and was, therefore, the most difficult part of the works. Fair progress was made in the first two years, and at the beginning of 1850 the foundations had been carried 650 feet from the shore. At that time a storm did great damage to the staging, but not much harm to the permanent work. The rate of progress throughout was camparatively slow. The greatest advances were made in the years 1849 and 1861. The average yearly advance, from 1847 until it's completion in 1871, amounted to 91 feet a year.
The work was carried out under three contracts - the first for 800 feet, taken in 1847; the second for 1,000 feet, in 1854; and the final one of 300 feet, in 1867. The total sum paid to contractors was £679,368, working out at £323 10/- per lineal foot for its entire length of 2,100 feet as completed in 1971. After that date there was a large expenditure for constructing a fort at the end of the Pier, and a projecting apron to secure the base of the structure from being undermined by the current. The fort was armed with two 81-ton guns, fixed in a revolving turret, and at large expense a magazine was built under water, the total cost being £150,000.