David was trained for the sea in the school ship HMS Conway, then the last 92-gun ship of the line left afloat, when she was swinging to moorings in the Menai Strait, which separates the Welsh mainland from the Isle of Anglesey. During the holidays after his second term aboard, the ship ran aground on the mainland shore near the Menai suspension bridge.  She was being towed through the strait to a temporary anchorage off Bangor in 1953, pending a refit in Liverpool.  When the tide went out, her back was broken, and she was wrecked.

Aboard, cadets had slung hammocks, and kept their belongings in black wooden sea chests.  The main deck was partitioned during the day to form classrooms for lessons in navigation, ship construction and seamanship as well as standard academic subjects, which included Spanish.  Communication with a small dock on the island was effected by semaphore and aldis lamp Morse signalling.

Junior cadets had spent their first two terms in dormitories in part of the Marquess of Anglesey's stately home on the island, and this continued to be the case after the grounding. However, wrecked cadets had to spend a term in army bell tents before a wooden camp was built. A far better stone college eventually opened, but reduced demand for seafarers led to its closure in 1974.

HMS Conway wore the Blue Ensign of the Royal Naval Reserve with the Conway castle emblem in the fly, her boys in training, principally for the Merchant Navy, having been given the honorary rank of Cadet RNR (Royal Naval Reserve). John Masefield, whose poem Sea Fever is familiar to millions, and who was British Poet Laureate between 1930 and 1967, was a cadet in HMS Conway between 1891 and 1894 when the ship swung to moorings off Rock Ferry in the River Mersey.  A website dedicated to the ship can be visited at www.hmsconway.org.  The site is owned by Alfie Windsor (HMS Conway 1964-1968) whose book HMS CONWAY 1879 - 1974 has a forward by His (late) Royal Highness the Duke of Edinburgh, and can be ordered through the site.