His father, Simon told the inquest, James had a tendency to become “hyper-fixated” on things and had developed an interest in air pistols and modifying them, including, it is thought - the one involved in his death.

James Keeping, 25, who had been suffering mental health problems, had been drinking and was argumentative on the day he died at the family's £1.5 million Oxfordshire farmhouse.

His father, Simon told the inquest, James had a tendency to become “hyper-fixated” on things and had developed an interest in air pistols and modifying them, including, it is…