IN the early wartime months of 1940, the French destroyer, Le Maillé Brézé, had been a busy ship, escorting gold reserves to the safety of Canada, then battling with German naval forces off Norway, and escorting French Alpine troops to assist in the defence of Norway against a German invasion.

At the end of April, she returned to her "adoptive home port" of Greenock to repair, refuel, and rearm.

During the process at the Tail of the Bank, in the early afternoon of the 30th of the month, she was rent asunder by an unholy explosion, followed within an hour by two more.

Less than six hours later, and despite heroic efforts to save her and her crew - at great risk amidst the smoke, roasting plates and popping shells - she slid beneath the waves and settled on the bottom shrouded by hissing steam, smoke and fumes from the fires and her roasted hull.

In the morning, only her mast protruded rakishly above the surface to mark what was now a war grave for 21 men trapped below in their forward mess deck by a jammed hatchway - next to a magazine filled with ordnance.

Forty-seven were injured, some rather badly, and were recovered for treatment. Seven who had perished above decks were later laid to rest in Greenock Cemetery.

Two British seamen, who had rushed across from the aircraft carrier HMS Furious with two officers (one a RNVR surgeon) and boarded the Maillé Brézé foredeck with them, were lost in the third explosion while applying a hose rigged and passed over by the merchant ship Barfield.

In 1954, a salvage operation moved the wreck across the river to beach it at Ardmore, where the remaining munitions were removed (including 18 depth charges).

In August the remains of the 21 trapped sailors were taken ashore with full military honour and Requiem Mass in St Laurence"s Church, Greenock, then returned to France for burial. The wreck was taken to a Port Glasgow breakers yard and broken up in October.

Rumours as to the cause of the disaster were rife for a time after the event. Later (unofficial) accounts published in the 1960s and 1980s "floridly" presented some contradictory versions of - sabotage by Vichy spies; a torpedo exploded while being moved; a live torpedo slipped from the tube under repair.

There was no Vichy at the time; Marshall Petain formally surrendered France on 22 June 1940, and a more immediate report by a naval intelligence officer to the Admiralty which, with parole evidence of hospitalised survivors, indicated that a live torpedo in the No 1 starboard torpedo tube (and the ship had seven tubes in addition to her seven five-inch (14mm) guns), swung in for maintenance, had fired off into the deck. The artificer working on the tube - and his account - vanished in the first, fatal explosion.

Even 64 years on those who perished on 30 April 1940 are not forgotten.

The memorial erected and unveiled on Lyle Hill in 1946 commemorates all French naval and merchant seaman who fought in the Battle of the Atlantic and elsewhere.

The memorial, an upright anchor with the stock forming the French French Cross of Lorraine, was Dedicated to their memory by the Free French Naval Padre, Father Olphe-Gaillard. The town of Greenock undertook to care for it and look after its upkeep.

• Story by Francis Wallace, a retired accountant and company director from Whitburn, West Lothian. His interest in the Maillé Brézé goes back to his first visit, as a van boy, to Lyle Hill. The day was 27 May, 1940, and during a lunch stop, his Italian driver and his brother told Francis how they had witnessed the tragedy from that spot.