AN “evil” Huddersfield man who drew his schoolboy sons into a plot to butcher their much-hated mother must stay in jail for several more years.

David John Howells, now 59, was jailed for life at Leeds Crown Court in February, 1997, after he was convicted of murdering his wife, Evelyn.

At the Appeal Court in London yesterday Mrs Justice Swift described Mrs Howells as dominant and abusive and “with many deficiencies as a wife and mother’’.

Howells was appealing for a cut in his jail term. But he was told he cannot apply for parole for another six years.

Even then he may not be released.

After reviewing Howells’s case Mrs Justice Swift ruled that he must serve at least 18 years for the murder.

However, after he is given credit for the time he spent on remand before being sentenced that means he can seek parole in October, 2013.

Howells’s sons, Glenn and John – then respectively aged 15 and 14 – made no secret of their hatred for their mother, said the judge.

Both boys were sentenced to be detained at Her Majesty’s Pleasure for the parts they played in her murder.

The prosecution said that in August 1995, Howells plotted with his sons that they would kill their mother – a teacher at Newsome High School – while he was playing an away match for his darts team in Huddersfield.

The evidence was that Glenn killed his mother with 10 hammer blows as she sat in her living room at their home in Dalton, addressing an envelope.

His brother may also have played an active role in the murder, although he was primarily accused of helping Glenn dispose of the evidence.

They then disturbed the house to make it seem that their mother’s murder had happened during a burglary.

Mrs Justice Swift said psychological evidence disclosed that the boys had been emotionally damaged by their mother’s ill-treatment.

She kept a tight rein on the family finances and had also carried on a longstanding affair with a family friend.

Mrs Justice Swift said the over-riding motive for the crime seemed to be her family’s desire to “rid themselves of the person whom they considered was making their lives a misery’’.

The trial judge had described Howells as a “thoroughly evil man who groomed or indoctrinated his sons to kill their mother while he was safely beyond suspicion as an actual participant’’.

His lawyers disputed the trial judge's branding of him as the prime mover in the crime.

But Mrs Justice Swift said: “The offence involved a high degree of planning and premeditation.

“The day was chosen and Howells prepared his alibi with care.’’

Mrs Justice Swift added that Mrs Howells had been vulnerable, in the sense that “she would have been totally unaware that her sons represented a threat to her and was defenceless against the attack’’.

Her husband had shown no remorse and his encouragement of his sons to commit the murder while he remained at a safe distance was also a “gravely aggravating feature’’.

Mrs Justice Swift added: “There was little, if any, mitigation available to Howells.

“All that could be said was that he had been exposed to the stress of living with a difficult woman who had been unfaithful to him and had made his life, and that of his sons, a misery’’.

Glenn and John Howells had been told after their trial that their tariffs would be set at 10 years and seven years respectively.

However, on appeal their minimum terms were later reduced to nine years and six-and-a-half years respectively.

Their father argued that this created an unfair disparity and that he, too, deserved a cut in his minimum jail term.

However, Mrs Justice Swift said: “Given the youth of Glenn and John Howells the applicant’s position as their father and the influence he must undoubtedly have wielded over them, a considerable disparity in tariff was both appropriate and inevitable’’.

The judge emphasised that, even when Howells completes his 18-year tariff he will only be freed if he can persuade the Parole Board he poses no serious public danger.

When, and if, he is freed he will remain on perpetual ‘life licence’, subject to being sent back to prison if he puts a foot wrong.