I bet Nigel feels relieved that the "knock on" did not cost Racing.
He missed the knock on, fair enough, you can't see everything; I thought it was a knock on too until I saw the replay.
His mistake was, not letting it play out to allow the try to be scored, and then going back to check with the TMO
Agree.
Something that Mike Fraser does well.
Only problem in NO's case was he was SURE it was a knock on. Had he any doubt I'm pretty sure he would have checked after the try.
The commentators were so sure it was a knock on, they were calling for a YC for deliberate.