Ten years on, Andrea Congreaves has proved him right. Next month, the Epsom-born Congreaves, now 6ft 2in, begins her professional career in America for the Charlotte Sting in the inaugural season of the Women's National Basketball Association. She will earn over pounds 1,000 per week for the 10-week campaign.
Stimpson and Congreaves have clear memories of that night at the National Sports Centre. But Stimpson and the Crystal Palace's women's coach, Mark Clark, soon realised that her talent would dwarf the English Women's League.
After playing for three English clubs between 1987 and 1989, Congreaves won all-American honours with Mercer University in Atlanta. She has played in Italy and Spain for four years but will add to her 25 England caps in the European Championships this month.
"Paul had come to coach basketball at Carshalton High School in our lunch hours. I'd never even seen basketball then," Congreaves recalled.
"I'd been playing netball, running 200 metres, throwing the javelin, doing the high jump - going for any sport I could. But basketball hooked me right from the first. It was the thrill of it, the speed, the physical side, especially compared to netball which was so static.''
Stimpson, 37, still England's most capped international player, said: "She was very tall, extremely athletic and incredibly talented for basketball and I persuaded her to come to Palace for more intense coaching. It was actually an under-pumped volleyball that she dunked, so she could grip it with one hand.''
Dunking is beyond the reach and athleticism of all but a few women players, even in practice. Congreaves said: "We were doing a jumping drill and I kept touching the rim, which I wasn't supposed to be able to do. Then I grabbed the rim and pulled the basket down, which I definitely wasn't supposed to be able to do.
"People in the gym started calling out in 'give her a ball, give her a ball.' So I ran in and dunked it, right-handed. I landed, looked round and the whole gym had stopped. No one was moving, everyone was looking.'' But she's never tried it in a game. "Far too scared," she added.
Congreaves continued, "I've always had a problem with self-confidence. I'd go along at my own pace, convinced I was developing OK, until someone convinced me otherwise." When the WNBA scouted her at Italian club Como, she assumed they were looking at two team-mates.
Clark, now assistant to Billy Mimms at the Budweiser League champions, the Leopards, also coached Congreaves at Brixton. "Mark and Paul were always telling me I had the talent to go to the top. When I was only 17 Mark said: 'You know you're good enough to play in Italy,' but I'd just look at him and say, no, I don't know that."
Last season, with Como, she reached the last four of the European Super League. Clubmate Catarina Pollini has also been drafted to the eight-team WNBA, along with two other Continentals - Eva Nemcova, of the Czech Republic and Frances Isabelle Fijakowski.
Congreaves, now a veteran at the highest level of European basketball, knows what to expect next month. "This league will be like taking all the most talented players and all the most talented teams you've ever faced and playing them every single game.
"Words can't explain how I feel because I still can't believe it."