Diana 'shot at in Hyde Park'

"The Princess of Wales once looked me in the eye and told me that someone had taken a "pot shot" at her in Hyde Park. At first I thought she was joking. She was not. She actually appeared to be telling me that she - the most famous woman in the world, icon of fashion and queen of hearts - had suffered and survived an assassination attempt in London's most popular open space. In daylight.

"She must be mad, I thought, recalling the furious rumpus when she was shot with a mere camera in a gym. For someone who had narrowly escaped death, her story lacked conviction, to put it mildly.

"She watched the thought pass across my face (she had an uncanny gift for that) and so I quickly replaced that thought with another: she's not mad but she is setting me a test.

"Like Sir Walter Raleigh sucking up to Elizabeth I, I was expected to take off my cloak of healthy disbelief and let her walk right across it. At a time when she imagined enemies everywhere, nothing less would reassure her of my loyalty.

"I failed the test. As her senior adviser, my job was to keep her in touch with reality. If she preferred fantasy ... well, there would be no shortage of people competing to share it with her. In the process, they would validate it in her eyes and sow the seeds of even taller stories in the future. That was not the Princess I had joined the Royal Household to serve, eight years before. I felt I could no longer do my job and resigned within weeks.

"I suppose many close aides to tricky big-shots question their boss's sanity from time to time. Right from the start, I knew she had more reason than most to feel stressed. I remember standing in the tunnel at Wembley before the 1988 Cup Final. Outside, a packed stadium awaited her appearance for the prematch ceremonies. Inside, in the gloom, I watched her take a deep breath, straighten her jacket and put on her "royal" face. She caught my eye and winked. In the midst of her own nervous preparations, she still made time to reassure the new boy.

"I came to know and admire that same daily ritual as Diana Spencer, still partly the under-confident teenager, transformed herself into the Princess of Wales, every inch the professional, dazzling royal celebrity. It took a unique set of talents plus guts and determination to make the transformation but she did it flawlessly every time. Talking to old soldiers and dying children. Talking to drug addicts and archbishops. Talking to presidents and to prostitutes. Talking to tramps and, yes, to the mentally ill; not just the benign successes of "care in the community" but also the outcasts of Rampton and Broadmoor.

"I will never forget the look on her face as we drove away from her first visit to a high-security mental hospital. If she ever had been "disco Di" the brainless clothes horse, she would never be again. Memo to any who talk glibly about flaky Di: this Princess witnessed madness up close in ways and in places you never will."