Former royal butler Paul Burrell said he was "sick to his stomach" when he received a phone call from a man saying he had kidnapped his wife, a court has been told.
Mr Burrell was the victim of a series of threatening phone calls made to his business in which the caller also threatened to place an "incendiary device" at his flower shop, Chester Crown Court heard.
A jury of seven men and five women took just 22 minutes to find in favour of the prosecution case against Bulgarian Slav Mitev, 50, who harassed and placed Mr Burrell in fear of violence.
At the start of the one-day trial Judge Elgin Edwards, the Recorder of Chester, ruled that Mitev, of Station Road, Wood Green, London, was not fit to enter a plea to the charges due to his mental state.
Judge Edwards told the jury that they just had to come to a unanimous decision about whether or not they believed he had committed the acts alleged.
Following the jury's verdict, Judge Edwards said: "It's a very sad case and has had a very upsetting effect upon Mr Burrell. The defendant quite irrationally seems to blame Mr Burrell for various matters which are not his fault."
At the start of the trial Mr Burrell, 53, took to the witness stand wearing a pin-striped suit, blue shirt and yellow tie, and re-lived a number of phone calls which were made to Paul Burrell Flowers in Farndon, near Chester, in June last year.
In one call, Mitev made threats to set his shop - where he was living at the time - on fire. He then received another call a few minutes later which he said was the "most disturbing" because it referred to his wife Maria.
"I said 'she is in America'. He said, 'no she's not. Can't you hear her?'," said Mr Burrell. "And what I could hear in the background was a woman sobbing and someone crying saying 'please help me, help me please'."
The case was adjourned for sentence and further psychiatric reports on a date to be set. Mitev was granted conditional bail and ordered not to contact Mr Burrell or his family by any means, not to enter to county of Cheshire and to keep attending doctors appointments.