Colthurst was a catalyst when bringing Andrew Morton’s 1992 book, Diana: Her True Story, to life. When the journalist was working on the project, Colthurst would bring Morton’s questions to Diana and deliver her taped responses to him. "I peddled in with a briefcase in the bicycle basket. And you know, initially, I sat and I read out the questions, but that was too slow for Diana," he revealed.

"She snatched the questions away from me and then clipped the microphone onto herself and the tape recorder was on and away she went."