A man shot himself after a warning that he might have a gun was not passed on to the police, an inquest has heard.
David Nurse, 77, was found dead by a community nurse at his home in Gurnard, Isle of Wight, on 1 February 2018.
Police were not informed of his landlady's 999 call warning of the firearms risk, which was a "massive failure" and put Mr Nurse's visitors at risk of being shot, Coroner Caroline Sumeray said.
She recorded a conclusion of suicide.
Police were called at 09:16 GMT to the bungalow in Marsh Road.
The former musician, who claimed John Lennon as a close friend, was found dead with an unregistered pistol in his hand.
Two days earlier he had refused a food delivery, telling the driver he had taken "suicide pills" and would shoot himself and anyone who tried to intervene, the inquest heard.
His landlady, Kuki Waterstone, dialled 999 that day, reporting the firearm threat.
The call handler said she "spoke to somebody" and "made them aware" but could not remember who she told.
Control room supervisor Michelle Cassell said she was "not aware" of receiving the information.
Ms Sumeray said the call handler had paused the 999 call and "in all likelihood, she did go and speak to somebody else".
She said Mr Nurse was depressed about his failing health and had called an ambulance 200 times to make him cups of tea or escort him to the toilet.
In a statement, Isle of Wight NHS Trust, which operates the emergency call centre, said it had "revised existing processes" for firearm risks.
Outside the hearing, Ms Waterstone's husband, Nigel Harley, said John Lennon had been best man at Mr Nurse's wedding and that he had found a picture of the pair taken on the big day.