London, Jan 08: A surveillance expert has told the ongoing inquest into the death of Diana, Princess of Wales of how he heard a ‘beep’ from a wall dividing her bedroom at Kensington Palace from the one used by her then hubby Prince Charles.

Electronics expert Grahame Harding was hired by Diana in 1994 to sweep her apartment for listening devices, two years after her separation from the Prince of Wales.

Now, he admits that the noise could very well have been the result of a ‘bug’.

Mr Harding told the inquest that Diana told him that she feared she was being spied upon, and that ‘dark forces’ around her.

However, he insisted that she did not elaborate on who or what those forces were.

“The Princess was concerned that in her apartment at Kensington Palace there may have been devices for listening to conversations,” The Sun quoted him, as telling the inquest.

“She asked me if it was possible to detect such devices. It is. She never told me who she suspected was spying on her and said there were dark forces — and never really expanded on that in any way.”

Mr Harding then used a tracking device to sweep the palace, a process he repeated thrice over the course of the next three months.

And while he did not find anything, he did note a transmission behind a wall one day in the room Charles used.

“I did not find anything apart from one particular day when there was a transmission behind a wall. There was another room off her bedroom used by the Prince of Wales — for what purpose I had no idea,” he said.

“My equipment detected an electronic signal which indicated a possible bugging device was present behind the wall.

“I could not get behind the wall. There was nothing altered to the fabric of the wall that I could see. A day or two later the signal had gone when I did another sweep.

“The equipment I use is pretty black and white. If a device had been there it would have to be receiving. I can’t give an explanation to the reading.”

Though he conceded that the signal may have been caused by “innocent electronic equipment in another room”, he said that it was “very similar” to a relay bug that ‘transmit speech’.

“It would have been able to transmit speech, nothing more. She never said what she would do with the results and never mentioned she had done anything about it.”

The inquest also heard from retired Royal Protection officer Chief Supt Colin Trimming, who revealed that Diana was convinced that the British secret services were spying on her.

A note made by a senior officer at the time stated: “She had been told, without any doubt, that five people from an organisation had been assigned full-time to oversee her activities including listening to her private telephone conversations.”

When asked if the late royal was taken seriously, Mr Trimming replied: “Yes.” (ANI)