Knowles was idolised by the Molineux faithful before walking out on the club in 1969 to follow his newfound religion.
He was converted after answering the door to two Jehovah’s Witnesses, who he said gave him meaning on the death of his father and sisters.
At the time Knowles was playing for Wolves with bags of potential and had even been compared with Manchester United’s George Best.
But after that point Knowles decided to change his life forever.
“At the time, I was an atheist,” Knowles told a national newspaper. “I didn’t believe in a God. I was happy to be a professional footballer, to play for Wolves. I am not bragging here. But I loved it and I was good at it.
“One day, two Jehovah’s Witnesses knocked on my door. I said to them: ‘Why did my dad and my two sisters, who’d done nowt wrong, die?’
“They came in and answered that question. They answered another question and then another I had never got an answer to. That’s how I became a Jehovah’s Witness.”
His family were against the decision to quit and they, along his team-mates, believed he would not stick it out.
On the following Monday, Wolves manager Bill McGarry laid out his kit for training.
And for the next 12 months Wolves laid out his strip each game in anticipation of his return but he never came back.
“Everybody – the manager, the players, my family, all the Wolves supporters – they all said, ‘He’ll be back in six months’,” said Knowles.
“My family couldn’t cope. My mum was upset, so angry. My brother Cyril (who played for Spurs) said: ‘Give him six months’. They couldn’t cope. Contracts were sent to me for 10 years.
“They thought I’d sign it. It’s the best decision I’ve ever made in my life. I’ve never regretted it. Not once.
“The Bible says ‘All men are created equal’. But when I put a football shirt on, there was a difference. People began to worship me. They idolised me.
“They treated me differently to an ordinary person. So, I thought: ‘What am I going to do?’
“The biggest problem as well was becoming a Jehovah’s Witness. People would say: ‘Why don’t you mix the two?’
“I said to them: ‘I can’t. I’ve got to give one up or the other.’ And I decided to give up football.”
Knowles made 174 appearances for Wolves and scored 61 goals but his last game was a 3-3 draw against Nottingham Forest on September 6, 1969, which was 49 years ago this week.
He settled into life in Wolverhampton with his wife Jean where he became a milkman, a tile seller and a window cleaner.