A report has found the deaths of Mick and Mairead's six children in a house fire the couple deliberately started themselves could not have been "predicted or prevented."
But Bernadette Philpott, the younger sister of Mairead, told ITV News' Paul Davies that things may have been different if it had been known earlier that Mick Philpott had a record for stabbing a former girlfriend.
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The attack happened in Leicester on Saturday evening.
The duke, who was in the Army for a decade, is stepping down from three roles in the forces.
A colder night - frosty as temperatures fall