The 8th Baronet of Hethel died after consuming a drug, an inquest heard.
Sir Thomas Agnew Beevor, 88, was found dead in his home, The Old Woodyard on the grounds of Hargham Hall, on January 22.
Two days after his death, his wife Sally Beevor found a suicide note within his belongings, King's Lynn Coroners' Court heard.
A post mortem examination found he had taken a drug close to lethal levels and his already existing health problems were a contributing factor.
Senior coroner Jacqueline Lake said there is evidence of intention to take his own life but there were also other considerations to take into account.
She said she could not be sure how much a role his background of respiratory and cardiovascular disease played in his death.
Ms Lake concluded the inquest with a short narrative verdict of drug toxicity against a backdrop of internal disease.
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