Charles first met Katherine in New York in 1988, when he was singing with a theatre group and she was a piano accompanist.
“We met quite accidentally outside the rehearsal hall and we fell in love with each other in about two minutes, and that was it,” he said.
Charles said he “hit the jackpot” when he met her, adding: “There was no parting us.”
Katherine took Charles back to the UK for a visit in 1989, as well as trips to parts of Wales that he admitted he “could not pronounce”, including Machynlleth and Llanfairpwllgwyngyll.
“It was just the beginning,” said Charles.
“We had a wonderful, wonderful relationship.”
At 08:06 EDT, on September 11, 2001, Charles kissed Katherine goodbye from their New York City apartment for the last time.
Exactly 40 minutes later, a jet smashed into the 97th floor of the tower – the very floor she had been working on, in a new job she had started less than a fortnight earlier.
“I knew instantly when it flew over my building – our apartment building – that it was a twin engine jet at full throttle,” said Charles, a trained pilot.
“I knew it so well that I called the FBI and told them… ‘That was no accident, that was deliberate’.”
A year later, when Charles met the FBI agent who took that call, he said the agent told him: “You were the first person to get us on to the fact that that was not an accident.”