Last summer Africa's first great footballer was invited by his friend and boyhood idol, Alfredo Di Stefáno, to the unveiling of Cristiano Ronaldo by Real Madrid at the Santiago Bernabéu stadium. An €80m purchase from Manchester United, Ronaldo was Portugal's new global star. Di Stefáno nudged Eusébio and said: "That would have been you."

Long before George Weah, Didier Drogba, Michael Essien or Samuel Eto'o there was Eusébio da Silva Ferreira, who wears a symbolic lustre no footballer can match as Africa's first World Cup approaches. Eusébio affirmed his immortality in the era of Pelé, George Best, Bobby Charlton and Johan Cruyff. Though his 64 international caps were acquired with Portugal – and all his deeds at club level achieved with Benfica, from 1961-75 – Mozambique and Africa can cite him as proof that their continent bred one of the game's all-time top 10 players not in the present age of Drogba and Eto'o, but 68 years ago.

So the "Black Panther" or "Black Pearl", as he was known, dubiously, must sense he is a figurehead for this tournament? "I do, I feel very proud. I don't feel a weight of expectation, but a lot of people are looking to me, with the first World Cup in Africa," he says. "It's something for the whole continent to be proud of, not just South Africa. For anyone born in Africa, any footballer, the biggest party in football is going down there for the first time."

The bare outline is that the first great footballer to leave Africa to pursue European recognition spent 13 seasons at Benfica, where he won seven championships, was Portugal's leading scorer from 1964-68 and helped bring the 1962 European Cup back to the Estádio da Luz, where he is immortalised in statue form and is still an ambassador for Lisbon's biggest club.

Eusébio scored 727 times in 715 appearances for Benfica and won the Golden Boot with his nine goals for Portugal in the 1966 World Cup. Four of those came in a 5-3 quarter-final win against North Korea. Forty-one goals in 64 outings for his adopted country is a record that lasted until 2005, when it was surpassed by Pauleta, a journeyman compared to this son of a railway mechanic, who played for nothing grander than a Coca-Cola and a sandwich until a conversation in a Portuguese barbershop shaped his fate.

The first talker was a coach from São Paulo, the Brazilian side who were touring Portugal after a trip to Mozambique (then Portuguese East Africa). The unidentified scout eulogised a young striker he had seen with a provincial club with ties to Sporting Lisbon. Listening was Bela Guttman, the Benfica coach, who flew within a week to Lourenço Marques (now Maputo). Eusébio could run the 100m in 11 seconds. Guttman outraged Sporting by buying the 18-year-old inside-left for £7,500 (Eusébio now says it was for €2,000, or its equivalent). Two weeks later he was playing for Portugal.

So far, so romantic, but the rancour between the two Lisbon clubs has endured. Even now Eusébio is irritated by the suggestion that Sporting were entitled to his signature. "I used to play in Sporting's feeder club in Mozambique. Benfica wanted to pay me in a contract to go while Sporting wanted to take me as a junior player for the experience with no monetary reward," he says.

"Benfica made a nice approach. They went to speak to my mum, my brother, and offered €1,000 for three years. My brother asked for double and they paid it. They signed the contract with my mother and she got the money. She put it in a bank in Mozambique, with a clause on it, saying that if her son didn't go to Portugal and become a great footballer she would pay the money back, because she had a good heart.

"There was a newspaper picture of her with all the money on the table with her arms round it. I had never seen such money in my life. Sporting tried to spread the story that I'd stitched them up, but it was the other way round, because they tried to take me for free while Benfica were willing to pay." To escape the kerfuffle, Benfica hid him in a house on the Algarve until Sporting had calmed down. At €2,000, or £7,500, whichever is the true figure, Eusébio was to become Portugal's finest player. Ronaldo is unlikely to have left Manchester for less than £200,000 a week.

The world Eusébio left was one of European colonies and lasting exploitation. Portugal's leading clubs farmed the country's overseas "possessions" for African talent. Portugal's imperialism in Africa can be traced to Vasco da Gama landing there in the 15th century on his way to India. Eusébio's pathfinders to Europe were Hilário, Matateu and Mário Coluna, who joined Benfica in 1954. The new star's salary – piffling, by today's standards – was twice the previous highest paid to an African footballer.

The day of his leaving remains in the foreground of his memory. And an anniversary approaches. He says: "Eighteen years old, 17 December 1960. In December of this year I will have been 50 years in Portugal. Always Benfica, it's a family to me. I'm an ambassador for them and the national team. I'm with them all the time."

Like most products of that gilded age, Eusébio describes the deprivations of his early years with pride, rather than regret, perhaps to amplify his achievements to the young and ignorant. "I was already a good footballer, I just wasn't a professional. We played with socks or newspaper rolled into a ball."

He is in London to support the Fifa-backed 1GOAL campaign, which has a target of ensuring 72 million African children can receive an education by 2015. This is no light ambassadorial duty for Eusébio, who has launched numerous charitable programmes in Mozambique and still holds dual nationality. "I have family there, fewer of them with time, and I have my friends. A lot of my family have passed over to the other side but I still have six relatives there," he says. He will be there for a fifth visit this year when he flies in this week.

"Every time I go back it gets a little bit better. You go to Africa now and there are a lot more football pitches and a better infrastructure, but it also depends on how it's managed after the World Cup."

Watching him rise from a table with his bow legs and impossibly tender knees, you see the high physical cost of 20 years in the game in a more brutal era. After Benfica, in 1975, he toured the North American Soccer League, turning out for Boston Minutemen and Las Vegas Quicksilvers among others. In the 1960s, Real Madrid's interest in him ceased when they saw how bad his weaker right knee was (six operations, in the same spot, have left a kind of ruin). His ambition was to emulate Sir Stanley Matthews and play on towards his 50s, but chronic knee pain forced him to stop at the age of 39.

As he tells that story about the Ronaldo unveiling, the question of envy creeps into the interviewer's mind. But he is straight on to it, like a loose ball in the box: "There is no jealousy. The generation I played with was the best generation ever. You don't have that now and I wouldn't change it for the money. It was all heart and that's why there were so many great players. Portugal, England, Brazil, Argentina: so many. That's why I'm so happy with what I had, to have been a great player. I'm happy to have been part of that era.

"Football nowadays is just commercial. Television commands the times of the games. The players are very good, obviously. I'm happy for the modern-day player who signs his contract and makes lots of money. The players of my era helped make that possible.

"I respect the football of today but the football of my time was better. Football hasn't got better, it has just evolved, from the ball to the boots to the shirts to the training methods – everything around them. Pelé, George Best, Cruyff, Garrincha would have been amazing players today.

"When we played Real Madrid and won 5-3 [in the 1962 European Cup final – Eusébio scored two] it was soaking wet and the ball ended up weighing a kilo. It didn't have a brand. That's why Pelé or Garrincha, if they played now, would be so wonderful. Consider their boots. There was no personalised footwear from Adidas. We'd have one pair for all surfaces, and the kitman would change the studs according to the conditions. Sometimes they'd do it in a rush and a nail would still be in there. You'd take your boot off and there would be blood from where the nail had penetrated your foot. Back then we made money, but we played for the love, it was all heart."

In this fraternal spirit he urges Africa's World Cup contenders to assume a strong group mentality: "The problem is that the players are quite individual. I wish the players would get together and work together. If that happened African football would take another leap forward." And he chafes when asked why Portugal have failed to convert talent into international trophies: "What a lot of people don't know is that Portugal have won tournaments, just not at senior level. Their juniors have always been very strong in World Cups and European Championships.

"The problem is that when people think of Portugal and these great players they forget it's a very small country. It's not easy. Portuguese clubs have won European trophies, but it's a very fine line between success and failure at international level and it's a very small country. Compare Brazil to Portugal and it's David and Goliath. The colonies in Africa – Angola and Mozambique – had four players in the Portugal side in 1966 and that's gone now because these countries have their own national sides. You've lost that stream of players."

Of Ronaldo he says: "I know him very well, he's a very good professional, a hard worker. At Real Madrid when all the players leave training he stays there and takes free-kicks, takes penalties, takes the ball on his own, dribbles. His work ethic is very good, without the coach asking him to do it. When my colleagues were back at home eating I'd still be practising and Ronaldo is the same, a real hard worker. I'm not a Barcelona fan but I very much admire Lionel Messi. I haven't seen him train. I know Ronaldo a lot better. Currently, Messi is the best player in the world. He writes his name all over the pitch."

To summon the spirit of his era – the 60s and early 70s – just ask whether Ronaldo might surpass him as Portugal's nonpareil. "I'm a footballer, not a pundit," he says. "Seven-times best footballer [in Portugal], top scorer at the World Cup, voted into the all-time Fifa top 10. Those are just the facts. I'm not sure whether anyone can surpass that. It's up to you guys to decide. I'm proud to say I've done something for the good of football. I don't compare myself to anyone."

He points to Carlos Alberto – Brazil's 1970 World Cup-winning captain, who is with him in London, and who scored arguably the greatest of all World Cup goals. "There are things you can't forget, moments in history like that."