Never the most naturally gifted player, it was Keegan’s determination that five years later brought him to the attention of Liverpool and their manager Bill Shankly, who took a liking to the slight youngster and told him he would one day play for England.

Before long, Keegan had established himself as a fan favourite at Anfield and was inspiring the Reds to league titles, domestic silverware and ultimately the European Cup during their golden era.

It was at that point, with the world at his feet, firmly established as one of the finest forwards on the continent, and with a glut of Europe’s top clubs after his signature that Keegan opted to walk away from Liverpool and head for the unfashionable port city of Hamburg and a club considered the ‘sleeping giant’ of Germany.

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“It was an exciting challenge. People asked, ‘Why would you leave Liverpool?’ But I just wanted something different. I wanted a new challenge. There was a sense of adventure in it.”

Keegan was something of a pioneer for English players moving to the continent. Today, the financial clout of the emerging Chinese Super League is changing the landscape of football’s transfer market, and Keegan concedes that, now as then, money plays a key role in the migration of footballers.

“It’s a wonderful time to be a footballer. There’ll probably never be as much money in the game as there is now,” he says. “Players now are privileged to be playing when football is at its height. I think ‘good luck guys’. The money’s there, they’re the ones who have to go out and perform. Why shouldn’t they take some of it?”

It’s a refreshingly honest attitude when in some quarters players have come in for criticism for a perceived lack of ambition in following the money to China. But then, Keegan helped lay the groundwork for footballers to become masters of their own destiny and maximize their money-making potential. He himself was dubbed ‘football’s first millionaire’.

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“I understand why people criticise. Usually it comes from disappointed fans who see someone like Oscar go from their club to a league they don’t quite understand,” says Keegan. “From the players’ point of view; you have to understand that they’re professionals. By the time they get around 33, [their career] is coming to the end. So, that’s their window of opportunity.

“These players that are going [to China], they’ve probably got a year left [on their contract] where they are. They get offered three years, and they think, ‘right that’s me until I’m 33’, on money they’re never going to earn again in their lives.”

“If you reversed it and said to these people that criticise them: ‘If you could move somewhere and someone will pay you twice as much money’, they wouldn’t say ‘oh no, I’m staying here’. If you put it in that perspective, they would do the same thing.”

So did the idea of a huge contract in a far foreign land in the twilight of his career ever appeal to Keegan?

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“It didn’t interest me. The China thing wouldn’t interest me if I was playing now. I personally wouldn’t move to a league that I thought was substandard. I went to the Bundesliga – that was a real tough league. But if you had asked me when I was a top player at 27 when I left Liverpool to go somewhere like America to play – which I could have done – I wouldn’t have gone because it wouldn’t have interested me to play in a league that’s not quite good enough. I went to Germany. It worked out great for me.”

Keegan’s three-year spell in Germany yielded 32 goals in 90 games, a first league championship for Hamburg in 19 years, a European Cup final appearance and two Ballon d’Or awards. His acumen in negotiating a release clause in his Liverpool contract also meant he became the highest-paid player in Germany as well as securing his image rights and several lucrative endorsement deals.

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“I came into football when players had no rights at all. Then we saw the change with the Bosman ruling and now players have all the power. When I was asked to extend my contract for a year at Liverpool, I said: ‘My fee is going to be half-a-million pounds when you sell me’. They agreed to that. When I went to Hamburg, I did two years. We won the league and turned the club around. They asked me to stay another year. I said: ‘I will, but then you fix my fee at half-a-million pounds’. And that’s what they did. So I could move wherever I wanted to. I probably was the first to do it.”

By 1980, Keegan’s negotiated contract meant he was able to take his pick from a list of potential suitors back in England. He opted for the unlikely destination of Southampton, choosing to play with friends at a club without lofty expectations in a transfer that shocked the football world.

“[Southampton player] Micky Shannon was my mate and I knew (Alan) Bally from England. It was different from any other club I’d been at because the expectation was huge at Liverpool and Hamburg.”

Success followed again with Southampton. The club secured a highest league finish the next season with Keegan dazzling as part of a free-scoring side.

“Of course, there’s a lot of emotion in football, but it worked out great for me. Things went on.”

Would he change any part of his journey?

“Nothing. No, I enjoyed every minute of it,” he says. “And I don’t look back much.”