Jacqueline Bartlam could be identified only by dental records, after her body was recovered from the blaze on April 25 last year.
The court heard how her son, Daniel Bartlam, had been inspired to carry out the killing by a plot in Coronation Street, where one of the characters John Stape, had killed a woman with a hammer.
Bartlam had claimed the killing was not murder because he had lost self-control.
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