Andrew Burfield, 51 and from Burnley, initially claimed the axe attack was an accident, but a post-mortem showed the mother-of-two was struck an estimated 12 times.

'Ferocious and cruel'

He changed his plea on the third day of his trial at Preston Crown Court.

The judge described Burfield's guilty plea as "a final recognition your game plan had failed".

Sentencing him, Mr Justice Goose said: "In your relationship… I'm satisfied you were manipulative and controlling while she was vulnerable" adding "it was a ferocious and cruel attack".

The jury heard Burfield travelled to Gisburn Forest in Lancashire in April for a picnic with Miss Kenyon.

He then claimed she had "bet" him he could not hit her can of Coke with his axe.

Killer claimed he was 'worried' about victim

A forensic pathologist described his claim that he hit Miss Kenyon, 33, accidentally as "completely implausible".

Burfield buried her body in a grave, which he dug the day before her death, in the Forest of Bowland in Lancashire.

The jury was told he sent messages from Miss Kenyon's phone to himself and her children after the murder.

Burfield even left a voice note in which he said he was "a bit worried" about her.

Initially, Burfield told officers he didn't know her whereabouts, then changed his version of events and revealed where he had buried the body.

'Torture' of police search

The court also heard a statement from Miss Kenyon's sister, Sarah Kenyon-Holden, who described the "torture" the family went through as police searched for her.

She said: "Katie told us she wanted to stop Andrew Burfield from being able to do what he did to her to other women.

"She wanted to stop him. She wanted answers. This cost her her life."