It was an ordinary day in his Perthshire primary, the day when the kids were given their routine hearing tests, but Redford's life was never quite the same again. The volume went up and up and up and still he heard nothing. It was the day they realised he was completely deaf in one ear.
In the course of a fine football career in the 1980s, most prominently with Rangers and Dundee United, Redford did what he could to keep the fact a secret. Team-mates would tease him about his hearing but very few knew the seriousness of his condition. He often could not hear if one of them shouted for a pass or tried to warn him an opponent was rushing in. When he did hear a shout he had no sense of which direction it was from. When he walked into a dressing room, on to a team bus, or sat down for a group meal, his first thought was to find a seat where his "bad" ear was against a wall.
"When I signed for Rangers I remember going into the medical thinking 'aw naw, I really hope they don't test my hearing'. I was dreading it. The doctor said my blood pressure was high and I think that was because I had worked myself into a lather that if they found out I was deaf they might not sign me. I remember the doctor saying 'do you have any problems' and I think I said 'ach sometimes I'm a wee bit hard of hearing on the left side'. He said 'that's okay, probably a bit of wax or something . . .' "
What Redford knew by then, and kept to himself, was that a childhood illness had caused irreparable nerve damage in his left ear. Whatever it was - maybe measles or some other virus - it happened when he was so young he had no memory of his hearing being any different. The outcome from that primary school hearing test was as much a surprise to him and his parents as it was to anyone else.
"I remember people talking away to me on my left side and they'd think I was ignoring them. School was awkward. I was shy anyway. I'm hearing you now, we're having this conversation, but when you're deaf it's a little bit harder to process the information. You're maybe picking up 75-80% of what's being said. In a football dressing room it could be a problem. Someone would say 'hey Reddy' and I'd be looking around.
"I tried to hide it. I was very self-conscious about it. People would joke about me being deaf but I didn't like to admit the fact. In some ways I was denying it. Some of the things being said could be merciless. Looking back, banter is just banter. It could be quite cruel, it can get quite nasty, but more often than not it's good-hearted banter. It made me a little bit more introverted."
The consequences of his deafness are explored in Redford's fascinating autobiography, Raindrops Keep Falling on My Head which is published next month. In the book, self-penned without the use of a ghost writer, he writes in depth about his deafness and also about the family tragedy of losing his seven-year-old brother, Douglas, when Ian was 12. Douglas passed away after a long battle with leukaemia and his parents' struggle to cope with that, and protect their other children, is a powerful pillar of an admirably candid piece of writing.
"It was really devastating. It was uncomfortable to write about but I felt if I was going to tell my story I had to tell the whole thing. Douglas contracted leukaemia but I wasn't really aware of what was wrong; it was just my sister and I knowing something wasn't quite right. He was never getting better and eventually after about five years he died. There was so much pressure on my mum and dad and I look at how they coped and struggled to cope. It was a case of two people who started out with a really happy family and how this affected them. They definitely tried to keep things from me and that in itself maybe caused problems. When my brother died I was in my first year at Perth High School. It was just before Christmas. He had gone through all the chemotherapy and the usual treatments and there had been a deterioration in his health. By the end it was too much."
He dedicates the book to his mum Elma and dad Ian, who have both passed away. His relationship with his dad was loving but occasionally strained. He remembers his dad repeatedly throwing a ball in the garden for him to head or kick against the garage door.
"In my early days there was a lot of anger in me, a lot of suppressed anger because of what happened to my brother and a lot of confusion about that. I would like to think I'm naturally a peace-loving person, I'm not a guy who goes seeking trouble. Dad felt the harder he was on someone, the more it was character-building. That was just the way that generation was. My mum and dad were great people. Dad's heart was in the right place but there was a conflict in the relationship. We were all affected by Douglas's death.
"But I look back on my mum and dad with real fondness despite the difficulties we had. They loved to come and watch me playing. I remember coming back from a game where I scored four for Dundee against St Mirren. Coming into the drive, the two of them were standing at the door and they were just so made up for me. To see the looks on their faces that day, it was just great."
The book title derives from the song written for the film Butch Cassidy and the Sundance Kid: sharing a surname with Robert Redford meant Dundee fans nicknamed the elegant midfielder "The Sundance Kid" . Raindrops also allude to Redford leading a life with far more hardships than most people assumed.
As the son of a Perthshire farmer he was seen as having been born with a silver spoon in his mouth, somehow different from and luckier than the others in football. "There was this attitude of 'oh yeah he's from a privileged background' but my father was working class, he was the son of a blacksmith and trained to be a blacksmith himself. He started the family business with next to nothing and built it up himself. I was almost made to feel guilty about it. Most of it, 95% of it, was poking fun, but I always got the impression that sometimes there was a bit of an undercurrent there as well."
He emerged with Dundee in the late 1970s and became Scotland's most expensive signing when John Greig paid £210,000 to bring him to Rangers in 1980. He stayed for five years, winning the Scottish Cup in 1981 and the League Cup in 1981/82 and 1984/85. Generally it was a barren time between the Jock Wallace trebles era and the Graeme Souness revolution.
"John Greig had probably as tough a task as any Rangers manager has ever had because as a player he'd enjoyed such great success and all of a sudden, without really having much more money to spend than the other top clubs, he had to unwind that treble-winning era and develop a new phase. It was an enormous task."
Redford is best remembered by Rangers for two big cup final moments against Dundee United in 1981. In May, the Scottish Cup final was goalless when his late penalty was saved by Hamish McAlpine, although Rangers comfortably won the replay 4-1. In November he brilliantly chipped McAlpine for a late winner in the League Cup final.
At only 25, Jock Wallace allowed him to leave for Dundee United. "I was sad to be leaving Rangers. Dad had just died and I was confused about whether I needed to be back up nearer mum. Football was almost the last thing on my mind but I'd always admired the way United played football and I felt their style of play suited my game. Jim McLean was responsible for getting me back on my feet. He was a difficult guy to work for, a very complex character. But he was a genius."
He played some of the best football with United as they beat Barcelona en route to the 1987 Uefa Cup final against IFK Gothenburg. His career wound down with Ipswich Town, St Johnstone, Brechin City and Raith Rovers, where he was due to take the very next penalty in the shoot-out if Paul McStay hadn't missed to cost Celtic the 1994/95 League Cup final.
Later he worked as an agent and then drifted towards golf tourism and promotion, even changing his status from amateur to professional in 2011. His son, also Ian, is a highly talented golfer. "I never had any serious aspirations of being a European senior tour player but I felt it would be good if I could have some relative success, like making a cut, which I did at a tournament in Spain. I finished tied 36th, which was reasonably respectable under the circumstances! The golf thing was something I thought I might develop into getting involved in tourism or that side of things but it didn't really materialise."
There is one other incredible element of Redford's story and his book. He is now 53, and when he turned 40 he began to notice he was losing the hearing in his right ear. He struggled to pick up even one-to-one conversations and developed tinnitus. Eventually his wife encouraged him to go for a test which revealed another problem, entirely unrelated to the other ear.
"The loss in the left ear is nerve damage; in the right ear it's to do with calcification of the bones. So I came back with a hearing aid and thought 'wow, this is fantastic'. All of a sudden I was hearing noises I hadn't heard for ages. Birds singing in the morning!"
Ear issues have been a permanent difficulty in Redford's life. Except once. "Playing for Jim McLean, I actually thought being deaf was an advantage. After his first couple of team talks I thought 'yeah this is definitely going to be a good thing.'"
Raindrops Keep Falling on My Head: My Autobiography by Ian Redford. Black and White Publishing (released November 14) £15.99