Mr Arnold, from Bebington, said: “It is one of thousands of shipping disasters, but this was so close to home and it remains the Royal Navy’s worst peace time submarine disaster.
“This will probably be the last major Thetis anniversary that families will be able to attend – I’m 71 now and in another ten years it’s unlikely so many people will be able to travel to Wirral.”
Thetis’s initial attempt at a dive was unsuccessful as the vessel was too light.
Lieutenant Frederick Woods, the torpedo officer, opened the test cocks on the tubes.
But, with the test cock on tube number five blocked by enamel paint, no water flowed out, even though the bow cap was open.
This confusion led to the inner door of the tube being opened, without the knowledge that the outer doors were already open and the tubes full of seawater.
The inrush of water caused the bow of the submarine to sink.
