William Henzell was born in Newcastle by 1786, and is one of the many Henzell's who settled in the All Saints/Ouseburn area of the city. The Henzell's were a Huguenot family, and alongside the Tyzack's and Maling's made their name as expert craftsmen in the Ouseburn area. The Henzell's specifically owned their own glassworks. You can see some Henzell graves in All Saints Church, where William was christened. Henzell likely worked at one of the shipyards on the North Shore - probably at St Lawrence or St Peter's. Here, he gained his reputation and status in the Pigots Directory of 1834. It was essentially a yellow pages listing occupations of individuals and well regarded go-to businesses.

By 1834, Henzell had moved down the coast to Seaham to open his own shipyard in the south west corner of the harbour. The harbour itself was not completed until 1835, but was located just on its periphery. It had its own small patent slipway and small engineering shed, and can be seen on the Ordnance Survey illustrated in 1856 just after Henzell ceased trading five years earlier. It labels the slip and a rectangular building at the bottom of the cliff.

It makes a lot of sense for Henzell to construct a yard here - The area was rapidly developing in the 1830s, with saw mills, saw pits and the harbour itself providing a supply chain of industries to capitalise on. The saw mill specifically will have been hugely advantageous given wood was the most vital resource to build his ships.

Henzell primarily built colliers for the trade between London and Newcastle. Most of the known vessels he produced ended up in the hands of Tyneside merchants, though some for the Wear. The first attempted built ended up washing off the stocks because of incredibly rough weather. The hull was ready for planking but was washed off and had to be broken up.

The first completed known vessel was the Lady Adelaide, a schooner built for the Thwaites of Sunderland in 1836. It was named after the daughter of the Marquess of Londonderry who was the majority landowner in town (infamously). His next ship constructed in 1837, Lady Alexandrina, was also named after Lord Londonderry's daughter.

The yard continued operations for another 15 years or so. At least 20 were built, focusing solely on wooden rigged vessels. There is nothing recorded after 1851, though he could possibly have continued in the ship repair trade until 1853 when the business was sold. He ended up as the publican of the Royal Oak on Pilot Terrace, and was here as landlord until his death in 1871.

The yard was sold to the Potts family in 1853. The Potts were a well known shipbuilding family on the Wear both before and after the move to Seaham. Edward Potts of the Seaham yard and William Potts Jnr of the Wearside yard are directly descended from William Potts Snr, who built ships at the Hylton ferry landing throughout the 18th century.

Edward Potts built his first vessel here in 1854, It was a small schooner weighing in at 44 tons for W Mackie for services between Sunderland and Peterhead. This was a relationship that continued throughout his tenure at the yard. Larger scale vessels were also built here, included a 241 ton Snow called William Penn for Messrs Pallister of Sunderland the same year.

The yard inherited and maintained the Henzell site, and did not move into producing iron ships. Therefore it likely continued to take advantage of the vast timber supply chains immediately west of the yard.

The last ship built by Edward was the Jane Duncan in 1861, another cargo Snow built for Sunderland shipping. He'd moved back to Sunderland and lived at Sans Street in the east end of the city but continued building ships at Hylton. He had passed in 1865.

Edward's brother Robert commenced at Seaham in 1861, and had constructed at least 10 vessels during his tenure in the town. He mostly constructed sailing vessels for cargo for various routes. Ships for trade from the Wear to the Med, Blyth to the West Indies and for Ireland were built here, demonstrating the international influence of the Potts name.

Robert also built the first ever paddle steamer in the town - The Countess Vane. This was built for Lord Londonderry and his harbour. Because of the size of the yard and slip it had to be built sideways but was successful. However, in 1901 the ship was wrecked inside the New Docks because of a heavy storm, which breached harbour constructions.

There was a huge fire at the yard in 1871 and no ships are known to have been built thereafter. The yard was not insured, and therefore likely didn't have the capital to recommence building. Robert endeavoured into the repair trade thereafter, and was rebuilt in a more limited capacity.

Robert died very suddenly at Seaham Harbour in 1880 at the age of 61, and was put up for sale in 1880. The sale included a blacksmiths shop, patent slipway and warehouse. Only one year later the Potts of Sunderland retired the yard also, and put their yards up for sale in 1881.

George Hardy, manager of the Londonderry Engine Works and Londonderry Railway, carried out ship repairs as part of the huge portfolio of work undertaken.