John Pile, alongside his Jackson Dock directly adjacent, opened a new graving dock in the Swainson Dock in 1856. It was to be leased by Wood, Spence & Co but directly managed by Pile. The dock is visible a year after opening on the Ordnance Survey with a boiler house, engine house and was connected to the vast tramway system in the area.

A year later, the complex was growing - 8 acres and employing an average of 1500 workmen which was a sizeable chunk of Hartlepool's population. Ships were made for both local customers - the West Hartlepool Harbour & Railway Company, and international - the Dantzig Steam Shipping Co. based in Germany. The firm actually acquired the West Hartlepool Steam Navigation Co., taking over its vessels and trade.

In 1863 2000 people were employed here as the firm divested and covered a wider supply chain. Rope, hemp and wires, masts and sails were all produced as well as wood being carved in house. The former Richardson Bros. shipyard at Middleton was absorbed also and ran by John Pile's brother, T H Pile.

Despite this rapid expansion, 1866 saw the closure of the firm. Their accounts were ruined by Overend Gurney & Co., a merchant bankers who had collapsed owing over £1billion in todays money which triggered a widespread financial scare, and henceforth a good chunk of the shipbuilding industry who used their services. The last ship to be built was a steam barge, Avon, which could carry 300 tons.

The yard was later taken on by Denton Gray, a well known yard primarily operating at Middleton. They had leased it for a period of 14 years. Operations started in August 1868, and was right away used for repairs in the dry dock. 700 men were initially working the complex, and the first ship to be built here by Denton Gray was the Ouse in 1869.

The yard became the main site of Denton Gray after leaving the Middleton Yard, taken over by the Withy firm. As part of the deal, they extracted 1/3 of the profits during the first 5 years of operations. Up to 1200 operated in the peak years during their tenure, matching the ambitions of the previous owners. Business continued to prosper with continued orders from German firms and local merchants.

By 1874, the partnership between Gray and the Dentons broke down. Richard Denton left the firm, and William Gray continued alone in the venture. Gray did well, winning the Blue Riband in 1878 having the maximum output for any British Shipyard. They launched 18, with 17 fully completed. He set up a marine engineering works in 1883 to fully incorporate the supply chain and build their own engines. Engines on the yard were previously brought in from places like Hawthorns in Newcastle. It provided employment for 1000 men.

This time also saw the first generation of steel vessels built. The Shagbrook was the first in October 1884, though also continued with sailing vessels and other varieties given the flexibility of the site. The worlds second bulk oil carrier was launched here, missing out by a Tyne yard by one day. Gray continued to prosper thanks to his knack of supporting prospective shipowners rather than just taking on contracts. Gray expected only a £500 deposit, providing finance for those who couldn't pay for the ship outright. This also allowed him to gain shares in my firms, taking partial control of almost every other vessel built in the yard.

In 1887, another shipyard was constructed in the Central Dock adjoining the Marine Works. Thereafter, the scale led to the firm becoming a Private Limited Liability Company, with William remaining as chairman.

William died in 1898 left a huge dent in the management of the firm. His only living son, William Cresswell Gray took on the yard. They saw further expansion in 1913, seeking land on the banks of the Tees to build even larger ships through a lease from the North Eastern Railway.

The war was a prosperous time for the yard, producing vessels for both the Shipping Controller and the Admiralty. Steam turbines were used for the first time. Monitors, patrol boats and tankers were all produced.

After the war, Sir Gray went into partnership with Lord Inchcape, Sir J Ellerman and FC Strick to form the EGIS Shipbuilding Co. He went from strength to strength, acquiring a yard on the Wear, furthering a portfolio already covering area from the Tees to the Wear.

Sir Gray passed due to illness in 1924, and the third William Gray took over. It was at this time the yard saw the first spot of trouble. The recession of the 20s meant building on the Wear and Tees winded up, though the core works at West Hartlepool remained. Work continued at a steady pace through the 30s though intensified with the war effort. All the companys drydocks were put to work for the Shipping Controller for repairs and overhauls.

Though orders continued after the war, it was the 50s where real issues set in. New orders started to become scarce because of new and cheaper builders abroad. Japan and Germany started to dominate the scene, while in Britain yards were hit with labour disputes and late deliveries. This led to prospective investors taking second thoughts. Shipbuilding ceased in 1961 with the Blanchland. A few more barges were made, but from thereafter only repairs were completed. The company went into voluntary liquidation in the December. The contents of the yard was auctioned in May 1963 and were then cleared.

The Swainson Dock has been subsequently infilled, with only the Jackson Dock (https://www.northeastheritagelibrary.co.uk/shipbuilding-archive/har006/jackson-dock%2C-shipyard) in situ. The site is now part of the car part for the Royal Navy Museum.