According to Wikipedia: During a telephone call in 1990, Guppy asked Boris Johnson (then a journalist at The Telegraph) to provide the home address of News of the World journalist Stuart Collier. Collier had been making enquiries into Guppy's background, and in response, Guppy wanted to send someone to physically assault Collier. Johnson never discovered the reporter's address, and the attack never took place, but a tape of the conversation was leaked to the press in June 1995.

There are certainly lots of references to the story in the papers from that time. I am confident if you searched long and hard enough we would someone somewhere has transcribed the exact words Johnson used.