He was found dead in his bath one morning in January by his former wife Sandy Nye, an inquest was told.
Mr Patterson, 52, earned more than pounds 8m from his successful computer dating agency. He had been a dynamic and energetic man, spending much of his wealth on his great passion - flying. After Ms Nye divorced him in 1982, he had a relationship with his secretary, Kim Sellick, with whom he had two sons, but that too broke down.
During the 1980s and early 1990s, alcohol abuse began to wreck his life, and in the years preceding his death he was a virtual recluse, trapped in his own home for fear of panic attacks, the inquest heard.
The day before his death, Mr Patterson, his assistant Mark Cowley and Ms Nye travelled from his home, Chesterton Manor near Oxford, to Ms Nye's home at Elm Manor near Wisbech in Cambridgeshire, to help him overcome his fear of going out.
That night, Ms Nye stayed at her other home in nearby Walpole St Peter after a rehearsal with her operatic society, and Mr Patterson stayed at Elm Manor with Mr Cowley.
Ms Nye found his body slumped in the bath the next morning, January 29. He had drunk four-and-a-half times the legal limit for driving - 367mg in 100ml of blood, enough to kill someone less tolerant to drink, the coroner was told.
Ms Nye told the inquest she arrived at Elm Manor at 9am.
"I went up to the bedroom and saw him in the bath, but it looked like he was asleep. I said, 'What are you doing sleeping in the bath?" and then I realised he was all grey," she said.
"He was sat up in the bath with his arms on the sides, his head was sideways and the water was just up to his nose and his hair wasn't wet."
A Home Office pathologist, Dr Nat Cary, told the inquest on Monday at Wisbech magistrates court that Mr Patterson died from drowning and chronic alcoholism and had probably slipped or fallen in the bath.
The coroner, William Morris, recorded a verdict of accidental death, saying that "for some reason or other he slipped under the water".