CHRIS PATON At half-past eight on the evening of October 9, 1968, Able Seaman Colin Paton had just finished a tensely charged six-hour watch on board the British nuclear- powered submarine HMS Warspite. He and the crew had been at action stations for more than three days, working on a secret mission in the Barents Sea to observe and record the efforts of the USSR to test a submarine-launched missile system.

Tired and hungry, the young submariner, later to become my father, had just made his way to the mess for a long-overdue meal when all hell broke loose. "I had just sat down when the boat tipped 65 degrees to its heel and 25 degrees bow up," he remembers. "A bottle of sauce flew past me into the clock on the wall, smashing its face. We'd obviously struck something, but I had no idea what."

The Warspite had in fact collided with the very Russian vessel they had been trailing. A sudden and unexpected change of course by the Soviets had not been identified in time, and as a result the Russians had ploughed straight into the British submarine's central conning tower, or fin.

"We had always had it drummed into us that if there was ever a disaster, get to the escape hatches, so I made a run for the nearest hatch in the torpedo compartment," says my father. "Once there, I realised the emergency tanks had been blown, in order to get us to the surface."

Through the panic, he made his way to the control room, where he was ordered to take over the steering and depth mechanisms. To do so, he was forced to knock out a terrified rating who, in his hysteria, was refusing to let go of the controls.

Once the British sub had surfaced, the captain ordered a medical team to prepare to offer aid to the Russians, despite the obvious dangers. But Warspite's radio operators intercepted them signalling to the Soviet fleet that they had been hit by a Nato submarine and had no casualties. Deciding it would not be safe to hang around, the captain retrieved his team - then gave the order to dive back under the water.

For the next few hours, Warspite agonisingly made her way to safety. On the assumption that the Russians would be looking for them, the captain put the sub on a circuitous route back home - yet the stricken vessel could proceed at no more than eight knots through the hostile waters. At one point my father remarked to a petty officer that he was glad they had got out of danger. The reply came back that they would not be out of it until they were back in a British dock.

"We were under no illusions as submariners. If we'd been detected in hostile waters, we would have had everything thrown at us," remembers my father.

Several days later, having made its way through the Barents Sea undetected, the Warspite finally limped towards the relative safety of the Shetland Islands. Under cover of night, the Navy transported a couple of carpenters to the stricken vessel by helicopter. To obscure the damage, they erected a wooden frame over the affected part of the fin, on to which they then fitted a black tarpaulin - enough to deceive any Soviet spy planes. The submarine then returned to Barrow-in-Furness for repairs.

To this day, my father remains appalled at how the Navy covered up the incident. "When we made it to Barrow, we were gathered into the boat's mess and ordered to go and have a drink and forget about it. I sent a telegram to my mother in Northern Ireland to say I was fine, thinking she would be worried sick. She had no idea what I was talking about. They didn't even inform our families what we had been through. It wasn't until a few days later that the government put out some half-hearted cover story to suggest we had collided with an iceberg. What we really needed was counselling, but the Navy didn't do counselling."

This lack of treatment would come back to haunt my father 20 years later. Having left the Navy in 1978, he eventually secured a job working as a railway conductor for First Great Western. On October 5, 1999, his 54th birthday, he found himself at the heart of an even greater disaster; one that resulted in the deaths of 31 people. As the train he was working on made its final approach to Paddington station in London, it was crashed into by a Thames train that had gone through a red light at Ladbroke Grove. Despite the fact he helped save many lives on the train, the tragedy caused him to suffer post-traumatic stress disorder for the next two years.

"I had treatment at the Priory clinic, and during this it became apparent that the earlier incident on the Warspite, which I had been ordered to forget about, had in fact been buried deep in my mind," he says now. "When the train crash happened, it was enough to release my anxieties from the much earlier incident. I wasn't just dealing with Paddington: I was suddenly having to deal with the Warspite crash all over again."

The logs for the submarine for the three months following the collision remain classified, despite being well beyond the 30 years within which such records are normally released. There has also been surprisingly little written about it, though I have been able to corroborate most of my father's recollections through former colleagues of his that I have since managed to trace.

Today, my father lives in Crete. For his sixtieth birthday, in 2005, my wife and I decided to buy him a present on behalf of our sons to show him how much we appreciated his efforts both in the Navy and at Ladbroke Grove. A simple Zippo lighter with the Warspite's crest on the side, engraved with a short inscription: "To Grandad, Happy 60th Birthday. Love Calum and Jamie. You Can't Keep a Good Man Down."