On the 100th anniversary of the explosion on board HMS Princess Irene which cost more than 350 lives, historians are no closer to deciphering the cause of the tragedy.

The explosion happened in Saltpan Reach, 400 yards off Port Victoria on the Isle of Grain.

Some 352 men – including 78 workers from Chatham and Sheerness dockyards – died, along with people on shore.

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The Princess Irene was a passenger liner converted to a minelayer, which had taken on mines brought down in barges from Upnor and Woolwich.

On Thursday, May 27, 1915, the mines were being activated ready for her third minelaying operation.

The dockyard men were there to strengthen the improvised gun decks.

At 11.12am there was a tremendous explosion, and then another. A dense cloud of vapour and smoke shot two miles into the air.

An officer on a ship 100 yards away said the noise was the most extraordinary experience of his life. The Princess Irene seemed to be hurled into the air a mile high in 10,000 fragments.

He could distinctly make out the forms of men amid the flying wreckage.

The end of the vessel was appalling, sudden and complete, he said. “She did not go down she simply went up and distributed her remains over an area of a score of miles.

From his position on the stern of HMS Actaeon, 500 yards away, Lt James Manners said he was slightly dazed for a few seconds after the explosion.

But on looking to where the Princess Irene had been he could see nothing but a mass of flames and white gas.

He said he saw two mines burst 40ft up in the air.

Two dockyard employees had left the minelayer in a government pinnace just minutes before the explosion and were lying on cushions in the cabin.

One of them, George Kilpatrick, said they had gone out to see what had happened but were compelled to seek refuge from the debris which was falling all about them.

When they were able to emerge once again from the cabin there was no sign of the Princess Irene, which they had been working just a short while before.

A section of steel from the Princess Irene weighing an estimated 10 tons was found on the Isle of Grain.

Following the tragedy, a board of inquiry was set up to investigate the cause of the fatal explosion.

Board member Captain James Fairie said the inquiry concluded the ship exploded through some unidentified cause.

But subsequent investigations suggested problems with the way the mines were primed, highlighting untrained personnel and hurried procedures.

It concluded a faulty primer could have been to blame, but offered no definitive answer.

Sabotage was even suggested by some after several similar ships suffered a similar fate. But there was no evidence of blame in the case of Irene, or any of the other vessels.

The coroner conducting the inquest into the deaths of the 352 men in the disaster was forced to record a similarly vague conclusion.

Mr CB Harris said HMS Princess Irene had carried the mystery of her fate with her.

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