A man who stabbed his partner and his best friend to death when he found them having sex on his canal boat was jailed for 12 years today.
William Cranston, 44, said he "lost his rag" when he discovered the couple making love, just feet from where he was sleeping.
The Sky TV engineer killed Kay Morton, 39, with a single stab wound to the heart and knifed Paul Wilkins, 55, several times, severing one of his arteries.
But he claimed he did not realise he was holding a 6in kitchen knife when he pushed the pair away from him, following the discovery.
Passing sentence, Judge Anthony Leonard QC told Cranston: "You are responsible for deaths of two individuals who did not deserve to die at your hands.
"It was clear when you gave your evidence that you showed remorse for what you had done and I felt that the remorse was genuine.
"I take into account that you tried to administer first aid as they lay in the cabin."
But he said the 12-year sentence was a necessary reflection of the "seriousness" of the two killings, Cranston's "short fuse" and the "sustained" attack he inflicted on Mr Wilkins.
Cranston, who has two teenage daughters from a previous relationship, said he "lashed out" at the pair to stop them leaving the room when he came across the scene in Stoke Hammond, Buckinghamshire, on September 7 last year.
After the attack he dialled 999 to call an ambulance and confessed his crime, saying: "I just caught my wife and one of my best friends shagging and I've lost my rag.
"The knife was on the side - I just stabbed them."
Told an ambulance was on its way, he replied: "I can't believe this. I can't believe I've done this.
"I can't believe this has happened to everybody. I just walked in there and lost my rag completely."
Cranston, originally from Newcastle upon Tyne, who wore a dark suit and tie, remained impassive as the judge passed sentence at Kingston Crown Court in south west London.
The defendant, who admitted stabbing the couple, was cleared of murder but convicted of manslaughter by reason of provocation at Reading Crown Court in Berkshire last month.
During the seven-day trial, jurors heard that Cranston, Ms Morton and Mr Wilkins had been drinking at the nearby Three Locks pub in the hours before the stabbings.
When they returned to the boat, named Secret, they drank and smoked cannabis while Ms Morton made dinner.
Cranston went to bed between 10pm and 11pm, saying he felt "drunk and dizzy", and had to get up early for work in Stevenage the next day.
But he was woken by a noise in the early hours and went into the canal boat's living room to find Mr Wilkins, a friend of more than four years, with his partner.
Describing the scene, Judge Leonard said: "You awoke and went into the day cabin and found Kay Morton sitting there just wearing a top and Paul Wilkins kneeling in front of her with his trousers around his ankles.
"You picked up the knife in your left hand as you passed the galley and went on to attack first Paul Wilkins and then Kay Morton."
The court heard earlier that Cranston's baby son, Kevin, died the previous February on the same sofa where he discovered Ms Morton and Mr Wilkins.
At the time, Cranston told police: "I found Kay and Paul having sex on the sofa. Paul jumped up and came towards me.
"I can't remember picking up the knife. When he came towards me, I just sort of lashed out to find out what was going on.
"Literally five seconds later, they were both on the floor bleeding to death, and I've got a knife in my hand."
Cranston dialled 999 and gave the pair chest compressions and mouth-to-mouth resuscitation but they could not be revived.
He threw the knife, which Ms Morton had used to prepare a chicken curry the night before, into the canal.
Sobbing as he gave evidence during the trial, Cranston told the jury: "I was just dumbstruck.
"I couldn't believe what had happened. I knew what had happened, but I just couldn't believe it."
When police arrived and asked him where the perpetrator was, he replied: "It's me."
Asked by Lynn Tayton QC, defending, how he felt following the attack, he answered: "I'm still devastated. I feel for everybody concerned.
"I've killed two people. And over what? I didn't even know I had done it to start with.
"I can't explain why. I think about it every day. I killed the woman that I love and a friend who I thought a lot of, and trusted. I feel terrible."
Cranston separated from the mother of his daughters, to whom he is still married, in 2003 after she had an affair.
He met Ms Morton shortly afterwards and said they "got on like a house on fire", quickly moving into a canal boat together.
But in early 2007, he caught her having sex with another man on a towpath beside a canal after she went for a walk with their dogs.
The pair decided to stay together but Cranston said he expected further infidelity, adding: "Kay blamed the alcohol but I didn't see how it couldn't happen again, because we were big drinkers."
When Ms Morton became pregnant with their son Kevin, Cranston said he questioned whether he was the father, a fact he then came to accept.
Less than three months later, the 55-day-old child - named after Cranston's brother who was killed in a house fire in Australia - also died.
The TV engineer told the court he was still struggling to cope with the baby's death when he discovered the scene, seven months later.
He said losing his son, following the deaths of his mother and father as well as that of his 28-year-old brother Kevin, left him depressed and unable to function.
"I had lost everybody, and now my kid's dead," he told the court.
Psychiatrist Dr Philip Joseph, who examined Cranston, said he had suffered "the ultimate betrayal" by Ms Morton, and that catching the pair having sex on the sofa where his son died was "the last straw".
A psychiatric examination revealed he suffered a "catastrophic loss of self-control".
In mitigation, Ms Tayton said: "He knows that he should be punished for what he has done.
"Provocation does not justify what he did - it at best explains to some extent what happened.
"He understands the dreadful, dreadful thing he has done."
Cranston, who was handed two 12-year jail terms to be served concurrently, will have time already spent in custody deducted from the sentence.
His friends and family refused to talk as they left the court.
Friends of the victims said they were too upset to speak after the hearing.Reuse content