We were mid-interview, in front of a crowd of 3,000 and a TV audience of 1.5 million, when, without warning, my right hand - which was holding the microphone - began to shake uncontrollably.
This was a live broadcast for Sky Sports and I was talking to Phil Taylor, who'd won his 16th World Darts Championship.
Up to that point, the interview had gone well, but now all I could feel was panic. After two years of trying to cover the traces and keep it secret, I was about to be 'outed' as someone who had Parkinson's.
Suddenly, that huge auditorium felt frighteningly small. My overwhelming instinct was to run. Instead, I switched the microphone to my left hand and tucked the shaking right hand under my left armpit to keep it still.
Exposure was averted. But it left me unbelievably scared. For my dad, Alan, had also had Parkinson's. And what started as a twitch in his right hand ended seven years later with him taking his own life in a cold dark cellar in our house in West Yorkshire when I was 17.
The reason for the suicide was the depression that descended on him as this dreadful illness took hold.
Parkinson's leads to a death of the brain cells that make dopamine, which acts like sunshine on your mood. As dopamine levels drop, so does your mood; that's why 40 per cent of people with Parkinson's get depressed.
Before his illness Dad had been a happy, sociable person, a real character. A big Yorkshireman and former rugby player, he'd always seemed to be physically robust. Yet, as the illness took hold, so his mood gradually declined and his nature changed.
I'm certain that hiding his illness and not talking about it added to Dad's depression.
After he was diagnosed, he was simply given a leaflet by the doctor and told to get on with it. He had to fight the battle on his own.
Keeping active: Dave presenting for Sky Sports in 2012, a year after his diagnosis
Of course, he told my mum, Audrey - but no one else. I worked out he had Parkinson's only after stumbling across a TV show on the subject when I was 14 - four years after he was diagnosed - and asking my big brother: 'Is that Dad's problem?'
Thirty years after he died I was told that I, too, had Parkinson's. Dad's health problems had returned to haunt me. The difference is that I'm not going to hide them.
The course of my life changed irreversibly on January 25, 2011. I had just spent 15 days presenting the darts for Sky Sports: more than 100 hours of live television, record crowds, record audience figures. I was on a high. Then the thunderbolt: the diagnosis.
Looking back, there had been plenty of signs. For the past four years my hand had gradually felt stiffer and I was unable to write as quickly.
I saw a physiotherapist, who actually suggested Parkinson's, but my reaction was: 'Don't be ridiculous.' I am quite healthy and fit, and cycle, jog or swim three times a week as well as playing five-a-side football. It didn't seem plausible back then.
In the back of my mind too, was the fact that just after Dad had died, the doctor told me Parkinson's 'is absolutely not genetic - don't worry'.
In 2010, I went to a specialist about a squint in my right eye. He told me it was a recurrence of a childhood squint that had worsened with age.
Around the same time my face and jaw felt stiff in the morning.
'I Googled my symptoms. When it came up with Parkinson's, I thought: "God, please no".'
Then about a year later I was previewing a recorded show and noticed something was clearly wrong. There I was on the screen, chatting casually with Phil Taylor and Eric Bristow. But why wasn't my right hand moving? It looked listless and plastic, like the hand of a mannequin.
Occasionally, I would also struggle to grip things - a cup, a microphone. I began to experience an occasional numbness all over my head and face, and my speed of thought sometimes slowed down. Occasionally, I limped.
None of these symptoms followed a neat time line. Sometimes I would have a limp, sometimes I would have a stiff hand, sometimes I'd feel fine.
The physiotherapist said these problems were not mechanical, but most likely neurological.
That really set alarm bells ringing. I Googled my symptoms. When it came up with Parkinson's, I thought: 'God, please no.'
When a neurologist starts asking you what you do for a living, the number of children you have and whether your mortgage is big, you know you're in trouble - and I was.
Various scans, blood tests and several meetings later, it was confirmed. I was 44 years old and I had the 'old man's disease' Parkinson's.
I walked home afterwards with my amazing wife Carolyn, baffled and crying. It felt like life had hit a buffer. Two small children (aged seven and 10), a great job, everything flowing along. Then this.
I couldn't face telling my mum on the phone. I got my big brother, who lives close to her, to go round. I'm so grateful he did that.
It was never going to be an easy conversation, it's like history repeating itself - except I want to make it through differently.
|Before the illness: Alan in 1951 and eight-year-old|