Todd might be one of the most decorated riders in history now but went into competition in Los Angeles with pragmatic expectations.
Together with Charisma, he had just come off a second placing at the prestigious Badminton Horse Trials earlier that year but says now Olympic success "was a pretty big surprise".
"It was my first Olympics and the horse had quite good form. Going into something like the Olympics, where you've got the best from everywhere in the world, I knew he could do OK but certainly wasn't banking on winning gold."
But the charming dark-bay gelding with a terrific work ethic and pedigree had different plans.
"When we came out of quarantine in America and got to our competition venue, Charisma was in top form," Todd says.
"From memory, it was pretty hot the whole time but he loved the heat. He was hopeless in the wet and mud so loved the firm ground."
Standing at 15.3 hands, Charisma was short for an eventing horse but had a hefty appetite thus gaining the nickname Podge. But Charisma had the hallmarks of a champion. Todd describes the gelding as "a brilliant little horse - nothing fazed him".
With the opening ceremony held the previous day, the three-day equestrian event began immediately at Santa Anita Park racetrack. "He did quite a good dressage," Todd says of their fourth-placed standing.
They climbed to second after the cross country but show jumping was never Charisma's best phase. The pair jumped a clear round to put pressure on leader Karen Stives of the United States.
"The only thing going through my head was, 'yes! I've got the silver medal'," Todd says.
As he stood wistfully on the fringes of the arena, cigarette in hand and with calm stature, he and thousands of spectators set their focus upon Stives' final ride.
"When Karen hit the fence down and I won the gold, it was unbelievable. I mean, I knew I'd won but it took weeks and months for it to properly set in."
It also impacted on Charisma.
"He had an even bigger fan club after that and got all sorts of attention," Todd says. "I've come across other horses that have had as much talent as him but he was the overall package, an absolutely charming horse. He was certainly my horse of a lifetime."
Reflecting on his win in '84, Todd still sees it as "one of the most defining moments of my career".
"Going back four years later with the same horse winning another gold medal [in Seoul in 1988] was another big highlight. You go into a competition like that where it's a dream to win a medal, let alone gold, and, even now when I look back on it, I still find it quite hard to believe it actually happened."