A former plastics worker was found dead in his home only when residents raised the alarm, after they smelled his decomposing body.
John Dodson, 69, was found by police officers collapsed on his bathroom floor in May.
At an inquest this morning, coroner's officer Sally Tupman said Mr Dodson, from Burritt Road in the Cambridge Road estate, "had not been seen for some time."
She added: "There was a light on permanently in the address.
"Residents raised the alarm and Kingston Council attended.
"[The council] contacted police."
Mr Dodson, who had worked for Arrow Plastics, had no known family members, West London Coroner's Court heard.
He had been adopted and both his parents were dead. He had no brothers or sisters.
A post-mortem, carried out at Kingston Hospital by Dr Olaf Biedrzycki, found Mr Dodson's body was "extensively decomposed", and his cause of death was therefore unclear.
Dr Biedryzcki found there were "no obvious signs of any medical treatment or significant recent injury."
He added: "There were no external or internal signs to suggest that trauma, violence or third-party assault had caused or contributed to death."
Assistant coroner Jeremy Chipperfield recorded an open verdict.
He said: "There is no reason to suspect any kind of foul play."
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