Defender Ring Jung-sun, who wore the number five shirt at the time, recalled Mr Kim's words of support.
"Before we left our homeland, the Great Leader invited us to see him.
"That day he embraced us lovingly and said: 'Europeans and South American nations dominate international football. As the representatives of the Africa and Asian region, as coloured people, I urge you to win one or two matches.'"
The next problem was getting to the UK.
With the Korean War fresh in people's minds, Britain did not have diplomatic relations with North Korea, and the Foreign Office viewed the team with suspicion.
Finally, the North Koreans were allowed to visit, on condition that their national anthem was not played.
The team arrived in the northern town of Middlesborough, site of their first matches.
Dan Gordon, the producer of a BBC documentary about the North Korean's adventure, called The Game of their Lives, remembers that the players had to work hard to qualify for the quarter finals.
"It wasn't all plain sailing for them," he said. "They played the Soviet Union and were well beaten 3-0.
"And then in the next game against Chile they were down 1-0 with the clock ticking away, maybe one or two minutes left, and Pak Sung-jin, the number eight, scored a tremendous equaliser, which then gave them a chance of at least qualifying.
"They played Italy in their final group game, and absolutely incredibly - the Italians were fancied to win the tournament - North Korea won, 1-0."
Middlesborough won over
By this time, the people of Middlesborough had taken the North Koreans to their hearts.
Dennis Barry, a Middlesborough fan, said his city fell in love with the style of football the Koreans played.
"They played good football - you know they were all small and that was a novelty in itself. It was like watching a team of jockeys playing," he said.
"But they moved the ball around really well. I think they took people by surprise, and they were very positive in their approach - they played attacking football, there was nothing defensive about their game, and the crowd got behind them from the way that they saw them play."
The Koreans were both delighted - and baffled - by the level of support they received.
"It still remains a riddle to me," said Ring Jung-sun.
"The people of Middlesborough supported us all the way through. I still don't know the reason why."
Once they had beaten Italy, 3,000 fans from Middlesborough followed the North Korean team to Liverpool for their crucial game against Portugal.
It was nail biting stuff. After half an hour the Koreans were winning 3-0.
Archive commentary from the match reflects the excitement:
"There's no question about it... these boys are turning form upside down. They look more the favourites now than Portugal do... the crowd are calling for more... and we believe that's possible."
But then Portugal's legendary Eusebio stepped in to score four goals. The Portuguese eventually won 5-3.
Even in defeat, the North Koreans were, by now, undoubted ambassadors for their country. The warmth was shared on both sides.
When Dan Gordon visited the players in North Korea, they were eager to return to Middlesborough. But were they just victims of a Communist system that had driven them to do well?
Not according to Dan Gordon, who says that modern football has only just caught up with the fast-paced style that the Koreans played:
"Football in 1966 was incredibly slow, and nowadays teams play like the Koreans did in 1966... I wouldn't call them victims at all... they were visionaries."