Bobby Womack is famished. He woke late in his Belgravia hotel and is now in a crazed hurry to get to the Oxford Apollo for a show to promote his new album, The Poet II. He hasn't had time for lunch, let alone breakfast, and the blood-sugar levels are dipping perilously. He asks the limousine driver to pull over in South Kensington, where he loses it with an assistant who can't work out how to make the sandwich he wants. "Lady, jes' gimme the meat!" he finally says with much exasperation.

Fifteen minutes later, as we head west on the M4, Womack is spreading various items of food across the back seat and shoveling them down, to the barely-stifled amusement of his third wife, Regina, and young son, Bobby Truth. To say it's mildly undignified would understate matters, especially from the viewpoint of someone who for a decade had worshipped Womack as one of soul's great singer-songwriters, and who is additionally delighted by the recent career uplift that's come with The Poet (1981) and The Poet II. Having chowed down and brought the sugar levels back up, Bobby almost immediately falls asleep; he spends the rest of the journey in that state.

Thirty years later, it occurs to me that he might have watched the sun rise with his old friend Ronnie Wood. "I been doin' this for 20 years now," he tells me on waking. "I'm fuckin' tired of it." Making matters worse, after 90 minutes of sporadic conversation with his wife we hit a long tailback and realise that Oxford United are at home for an evening game. Womack is going to be very, very late.

"I felt terrible last night," he tells me the next morning after a show he knew had been poor. "I felt like I was gonna die."

Now he is dead, at the age of 70, after experiencing yet another career upswing with 2012's The Bravest Man in the Universe, a heart-wrenching album masterminded by Damon Albarn and XL's Richard Russell after many years in which Womack again lost his creative way. On that intermittently brilliant record Please Forgive My Heart, you heard a lifetime's contrition as Womack looked back on decades of addiction and loss (including the tragic deaths of two sons and the murder in 1978 of his brother Harry). What you also heard in it, with his tortured gospel baritone fascinatingly framed by futuristic electro keyboards, was the good man inside him struggling to get out. He was nothing if not honest about his faults and flaws. And that was the man I got to know over three days in late September 1984, when the Poet II tour climaxed with three exhilarating nights at London's Hammersmith Odeon.

In my three days on the road with him – taking in a slightly surreal wander around Warwick Castle – Womack talked through his whole life and multifarious career. He spoke of the child-star days with his brothers on the gospel highway, and of their mentoring by secularised soul idol Sam Cooke. He spoke painfully of the ugly fallout from his marrying Sam's widow. He talked about playing guitar on Aretha Franklin sessions and of his deep immersion in the soul of Memphis and the Muscle Shoals sound studio.

Though he wrote I'm a Midnight Mover for wicked Wilson Pickett, Womack was himself far less conventionally macho as a Soul Man. He drew many elements into his signature R&B sound, from pop to singer-songwriter ballads to country music. (Predictably 1976's BW Goes C&W was his worst-selling album, but I like it.) He dug hanging out with Sly Stone, who influenced the coked-out funk of Communication, but he also liked cronying with the Stones, who had their second US hit with his song It's All Over Now.

"I wanted to be different from all the Stax cats," he told me on his tour bus. "It was like all of those acts was branded. It was the company that was famous, and I wanted my style to be so unique. I wanted to have a sound that wherever you took it, people would say: 'That's the Womack sound'." 

If Bobby Womack never forged a cohesive enough identity to achieve the fame of Sly Stone or Stevie Wonder or Marvin Gaye, his greatest songs – I Can Understand It, Woman's Gotta Have It, That's The Way I Feel About Cha, I Don't Wanna Be Hurt By Ya Love Again, When Love Begins, Friendship Ends, Games, Love Has Finally Come at Last, Please Forgive My Heart and many more – were the equal of most of theirs.

It is all over now. When the NME ran my on-the-road epic on 6 October, 1984, they called it "The Last Soul Man". "When Stax fell, that was the end of it," Bobby had said to me. "And when you look, there's nobody else out there. All those guys is either shootin' up or doin' nothin'. Out of all that music I seem to be the only guy I know who still does the same thing, but in a new world."

Three years later, Womack used the title The Last Soul Man himself – ironically for a slick album which wholly lacked the soaring emotional power of the two Poet albums. By the time The Bravest Man in the Universe came out, "soul" seemed an almost discredited notion in the new world of blingy over-production and rococo vocal mannerisms. Which is probably why the plaintive, inflamed Please Forgive My Heart was way superior to the R&B competition that year. Wouldn't it be nice if Bobby's posthumous Best Is Yet To Come album featured something equally devastating?

Of course we forgave Bobby's big troubled heart when it finally gave out on Friday. We forgave him because he sang so honestly and nakedly of the pain and the pitfalls of being loving, losing humans. That's the way we feel about cha, Bobby Womack. Now rest in the peace that you never found in life.

Life and soul

• Born 4 March 1944 in Cleveland, Ohio. His mother played the church organ and his father was a minister and musician. He was the third of five brothers.

• Began his career as lead singer of his family musical group, the Valentinos, and as guitarist for Sam Cooke, but was better known for years as a songwriter and session musician, working with the Rolling Stones, anis Joplin, George Benson, Chaka Khan, Ray Charles, Elvis Presley, Dusty Springfield, Aretha Franklin – and more recently with Damon Albarn and Gorillaz.

• Best known for hits Lookin' for a Love, That's The Way I Feel About Cha and Woman's Gotta Have It.

• In 1965 he married Cooke's widow, Barbara. They split in 1970 when she found him in bed with her 18-year-old daughter Linda. (Linda later married Bobby's younger brother Cecil and formed the duo Womack & Womack).

• Inducted into the Rock and Roll Hall of Fame in 2009.