'You've got to come and see this boy,' he said. 'It's like watching a Rolls-Royce. He will play for England.'
Rio was 15. He was a late developer, out of South London who wasn't selected for England at schoolboy level.
In the line of fire: Rio Ferdinand has stepped up into the high-pressure role of captain
Tony Carr, the youth team coach who is now West Ham's successful academy director, often used him in midfield in his early days because he was so comfortable on the ball.
But Pop Harry watched him in defence that day and rang when he got home. 'Son, you have got to look at this boy. He's something special, nearest thing I have seen to Bobby Moore. Passes, moves, glides and can defend. He's quick too. He'll be world class.'
Word went around our family; I was a Liverpool player at the time. My dad called me and I got the chance to look at him for myself when West Ham played Liverpool in the FA Youth Cup final.
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There was this gangly kid at centre half, really skinny and with long legs and the natural running style of a middle-distance athlete. But he could shift, cover the ground quickly, read danger. His name caught the eye too, because of Les Ferdinand's success at Queens Park Rangers.
Grandad has been proven right; Rio is following in Bobby's footsteps. He did become a top player and play for England. Now he is the captain.
Ironically, it's come at a time when he is not in the best of form. Rio knows this, but he has struggled this season with injuries. Once he returns from suspension, his first job must be to concentrate on his fitness then his form.
As a player, he will have the respect of the dressing room. He has developed as a man and grown up quickly since moving to Manchester United.
Playing in the spotlight is nothing new to him. He won't be a demonstrative shouter as a captain, but he will be comfortable with the responsibility.
There are some experienced senior players in the England dressing room - including John Terry, Steven Gerrard, Gareth Barry and Ashley Cole. They have also played in major tournaments before and will be influential on the team.
The captain of England during Euro 96 was Alan Shearer, but the leader was Tony Adams. In the dressing room, he was the biggest voice and he bullied and bossed on the pitch - just like he did for Arsenal, where he had the armband. It made no difference to his performance and his way of playing that he wasn't England captain.
Even though he wasn't the captain, he was the best captain I played under because he would influence everyone around him.
Before a game against Scotland, I remember him saying: 'This is Wembley, this is our house.'
It felt like he grew in size as he spoke and I was glad to have him in my team. Playing without the captaincy didn't dilute his performances and it will be the same for Terry now. It won't change the way he plays, either.
He can play only one way; head on the ball, fearless into tackles. You only need to look at his performances in the last two games for Chelsea, when he has been unaffected by the furore around him.
England's progress in the summer will not be damaged by what has happened here. The players will just be delighted to get on with playing.
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