He was knocked out when defending the European super-bantamweight championship at the Royal Albert Hall three weeks ago, and Oliver's life hung in the balance for 48 hours, the bulletins - "critical but stable" - ominous after a blood clot was removed from his brain.
Survival was one thing, quality of life another, Oliver's injury carrying also the fear of permanent disablement.
The American, Gerald McLellan, is blind, deaf and paralysed as the result of a brutal contest against Nigel Benn; Michael Watson, who came near to death after losing to Chris Eubank, is confined to a wheelchair. "God only knows how, but I got away with it," Oliver said last week.
We were sitting in the grounds of the West Lodge Park hotel not far from Oliver's home in Barnet, and it was about four o'clock in the afternoon. He had on a tracksuit and training shoes, and every now and again he reached for a cold drink.
I was watching Oliver. I was watching him sit there beneath an umbrella, a smile on his face, and I had it all figured out for myself.
This is a young guy, I was thinking to myself, who knows he is lucky to be alive but finds it difficult to accept that, at 23, he will never fight again.
Oliver remembers nothing of what happened between going to his corner for a routine defence against the Ukranian challenger, Sergei Devakov, and regaining consciousness in hospital. "It's all a blank," he said. "When I opened my eyes and saw Jess (Harding) looking down at me I thought I was coming around from a knock-out. An accident, a coma? I couldn't take it in and I still think I'm going to wake up and discover that it's only a bad dream."
Reaching to touch lightly a long, crescent-shaped scar that crosses from temple to earlobe on the right side of his shaven skull, Oliver marvelled at the neurosurgical skills that brought him back from oblivion.
"After what I've been through, knowing that others weren't so lucky, well, just to be here talking and walking around is a miracle. I can never be grateful enough," he added. Chuckling at the surgeon's story of being half-way through a curry when the emergency arose - "I ruined his dinner", - Oliver is nevertheless reluctant to watch a video of the contest.
"I know only what Jess and my trainer have told me. That I was knocked down near the end of the first round, hurt again in the sixth and counted out in the 10th. Everything before the fight is clear enough, warming up in the dressing-room, making an entrance, going to the ring and when I think about it now, not feeling as sharp as usual."
Four days before the fight, and not in a brash way, Oliver announced that he expected to win well within the championship distance of 12 rounds.
"Yeah, I know," he reflected. "Devakov hadn't done anything to make us think that he might be a difficult opponent. Busy, but not a banger." Oliver shrugged and shook his head. "I've been told that the real Spencer Oliver didn't show up, that it wasn't really me in there. Perhaps I took him too lightly."
Forty hours before we spoke, holding the sport blameless, Oliver watched boxing on television. "Just the thought made me nervous, but it was something I had to do," he said. Coming so soon after his release from hospital, Oliver didn't know whether he would find the experience disturbing. "I felt a bit strange but it didn't affect me in a bad way," he said, "so that's another step back isn't it?" Not though to that mysterious thrill he found in the ring. "Now it's about altering direction," I said. Oliver knew what I meant. "I need to work out what I'm going to do with my life," he added, "but for the time being I've got to take things easy."
Just six years old when he took up the hardest sport, Oliver couldn't wait for the opportunity to box competitively that came with his 11th birthday. He went on to win 75 of 85 amateur contests and had four amateur titles when he made his professional debut in February 1995.
By last year his fame was spreading, and he had acquired celebrity friends, the likes of actor Sean Bean and the East 17 singer, Tony Harvey. Just 10 days before he was carried carefully from the ring to a waiting ambulance, friends and family (he and Louise have a two-year-old son, Kane) distraught with anxiety, Oliver made a big impression when voted Young Fighter of the Year at the British boxing writers' dinner. Seeing and hearing Oliver for the the first time, guests from other sports were impressed by his manner. "Nice kid, the sort you want to do well," the football coach, Dave Sexton, said.
If Oliver's percussive style suggested that he would not have a long career great hopes were held out for him. Devakov had no record to speak of and negotiations were under way for a world title challenge. "Everything seemed to be going so well," Oliver said.
Passing by, a man spoke out to Oliver. "Good luck in whatever you do," he said. Oliver replied politely. "That's it," he then said. "Whatever I do. Well, I'd like to stay involved in boxing, train fighters, do some commentary work." The boxing club his family runs in Finchley, north London - his father has a furniture store in nearby Barnet - will help him pick up the pieces.
The drama of Oliver's plight raised again the question of how much can be done to prevent fighters risking the perils of dehydration, and consequent weakening, when attempting to make the statutory weight in their division.
It is unlikely that Oliver was entirely comfortable at the super-bantamweight limit of 8st 10lb but he insists that it wasn't a serious problem. Oliver counts himself fortunate. "I'm not bitter. Fighters know the dangers. How could I fail to think about Bradley Stone and James Murray dying from boxing injuries? But you never think about it happening to you," he said. So why do they do it, what impels them towards the ring? I was looking again at Oliver, his boyish face, the marks of his profession. "Look," he said, "I was proud of my title and I've got a lot to thank boxing for. It taught me discipline, showed me the world."