In the mid-19th century, the demand for a reliable standard of merchant navy officers had grown to the point where ship owners decided to set up an organisation to train, and indeed educate, them properly—the Mercantile Marine Service Association.

The ship they chose to accommodate the school, to be provided by the Admiralty and moored in the Sloyne, off Rock Ferry on the River Mersey, was the corvette HMS Conway.

In 1861 HMS Winchester took the name, but the one that housed the school for most of its life was lent by the Royal Navy to the Mercantile Marine Service Association in 1875.

This being wartime there was no official announcement of the move and local residents were startled one evening to see a picturesque Nelson-era ship of the line, a "wooden wall", entering the Menai Strait.

Subsequently, ship-to-shore traffic was across the Menai Strait to the pier-head at Bangor or to the Gazelle Hotel ferry terminal and she became something of a local tourist attraction.

He picked on Plas Newydd, the stately home of the Marquess of Anglesey, a large part of which had been vacated by the U.S. Army Intelligence Corps at the end of the War.

[7] What is termed 'slack' in the Swellies is actually a brief period of uneasy equilibrium between two opposing flood streams which typically occurs 1 hour 42 minutes before local high water, or at 09:08 on the morning of the move.

Owing to the strength of the southwest-going ebb, which runs at 8 knots during a spring tide,[8] there is a confused complex tidal flow among the numerous rocks and islets generating many powerful eddies.

"[5] In addition to the tide-generated streams in the Menai Strait there is also a non-tidal current, the Southwest Residual, a dynamic reaction which directly reflects wind stress in the Irish Sea.

[15] Conway's logbook shows she left the mooring at 0822 and arrived at Britannia Bridge at 0850,[12] which was the locally recommended time for starting the outward transit and Jones the pilot naturally advised keeping her going with the last of the northeast-going flood tide behind her.

The severe wind in the Irish Sea caused the stream in the Strait to turn to the westward earlier[9] which eliminated the brief slack water period.

Captain F J Durrant, marine manager of the towing company, observed "The anticipated ten minute slack water did not materialise.

After both tugs on full speed for ten minutes had failed to make any impression they were instructed to stand by at Menai Bridge Pier for another attempt to re-float her on the evening tide when there would be a better opportunity if the weather at sea moderated.

"Conditions on board were very bad with the after end of the ship from the mainmast sagging downwards, and the continuous sound of cracking, twisting, rending timber and rushing water below.

The school was first rehoused in tents loaned by the British Army pitched in the grounds of Plas Newydd, the seat of the Marquess of Anglesey, overlooking the Menai Strait.

These were quickly replaced by 'The Camp', temporary hutted accommodation in addition to parts of the Marquess's house already in use as a supplement to the ship's limited space.

During the 1960s permanent premises were built in the grounds of Plas Newydd, where Conway's last ten years passed in what is known in naval parlance as a "stone frigate".