The former British middleweight champion made a miraculous full recovery from being in a coma last March as a result of a bruising battle with Chris Eubank Jr. and was told by doctors never to take another blow to the head.
Despite this, the 26 year-old took part in a gym session and needed surgery to relieve pressure on his brain as a direct result.
Nick’s decision to put his life in his own hands was defended by a worried John in an interview with the Wiltshire Times.
“It’s like an addiction for him. Professional athletes like Nick find it impossible to stop doing what they love,” he said. “He must have thought he was getting better but he obviously wasn’t. He is the same, but he is stable. It is a case of taking it day-by-day.
“The gym owner and boxers involved are also at fault, but my main concern is making sure Nick is OK, not what happens to them. What he did was silly but he should not have been allowed to enter that gym in the first place.
On the moment he found out Nick was hurt again, John added: “I was expecting Dan and Nick to turn up at my house with smiles on their faces after Dan had called me but as soon as I opened the door I knew it wasn’t a joke. It’s such an agonising wait and it’s the second time we’ve had to go through it this year.”