A father has been jailed for life for murdering his young son and stabbing his teenage daughter.

Christopher Hawkins, 47, from Slaithwaite, near Huddersfield, West Yorkshire, killed his son, four-year-old Ryan, and seriously injured his daughter, 14-year-old Donna, to get revenge on his wife for having an affair and leaving him.

He was sentenced to a minimum of 21 years in prison for stabbing Ryan to death and was also given a 12-year sentence to run concurrently for attempting to murder Donna.

Hawkins launched the attack on September 23 last year - just one week after Ryan's birthday - after Donna arrived to pick up her brother, who had been staying with his father for the weekend.

During the eight-day trial, the court heard how Hawkins attacked his children before going to his local pub covered in blood and ordering a pint.

He then admitted his crimes to the police but claimed that he was "mentally insane" at the time.

Hawkins showed no emotion as the jury at Leeds Crown Court returned guilty verdicts after retiring for just over two-and-a-half hours.

The jury had been told that sheet metal worker Hawkins and his wife, Valerie Gee, had separated in May after she told him she no longer loved him.

He later discovered that she had begun an affair with a taxi driver while they were still living together, and was described as being "extremely unhappy" about the relationship.

The day before the attack would have been his 17th wedding anniversary.

His daughter Donna told the court how, as she tried to leave the house, her father apologised to her before stabbing her at least 13 times.

She said: "He turned around and said 'I'm sorry' and he just looked proper weird, angry, and I saw the knife and then he just went for me.

"He was stabbing me and I was telling him to stop and he just did it again and again. I was on the floor."

He stopped the attack when she told him she did not hate him but then turned his attention to Ryan, as Donna escaped bleeding into the street.

In her police interview, Donna said: "He said 'I'm going to kill Ryan now'."

Simon Myerson QC, prosecuting, said: "The defendant did this because he was angry at Valerie Hawkins for leaving him and taking the children away.

"He simply lost his temper, he did what he wanted to do, he didn't think about Ryan or Donna, he only thought about getting back at her."

Donna suffered multiple injuries to her face, chest, abdomen, arm and thigh.

Mr Myerson said Donna's chest wounds would have killed her if it were not for the first aid she received from passers-by in the street.

Ryan was stabbed nine times and was killed by wounds to his chest.

His body was found on the sofa in the house and, although resuscitation was attempted by paramedics, he was pronounced dead at hospital a short time later.

After stabbing his children, Hawkins went to his local pub, The Silent Woman, with blood all over his forearms.

He ordered a pint and told another pub customer he had stabbed his children.

When he was arrested by the police, he admitted what he had done.

Hawkins denied the charges of murder and attempted murder on the grounds of diminished responsibility, claiming that he was suffering from an "abnormality of mind".

Giving evidence during the trial, he said: "It wasn't me that day. It was like some evil inside me. I knew nothing of what I was doing."

He added: "I must have been insane. If I was sane that day, Ryan would be here now and my daughter would not have those horrific scars."

The court heard that Hawkins wrote a series of notes describing his anger at finding out his wife was having an affair and one which stated he and Ryan would die on September 16 - Ryan's fourth birthday.

Hawkins accepted the notes were in his handwriting but said he had no recollection of making them.

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