‘Completely still. It freaked me out at the time but I didn’t think much about it until I was at the supermarket a week or so later. I was pushing the trolley back to the car when I stopped. Right in the middle of the zebra crossing. Cars started beeping at me and there was absolutely nothing I could do. My arms were fine but my legs wouldn’t move. Everyone must have thought I’d gone a bit loopy, playing with the traffic like that, but I couldn’t control my legs no matter how much I willed them to move. Then they came unstuck and I shuffled off the crossing as quickly as I could, threw my bags in the car, and made my escape. It kept happening. Not every day by any means but frequently enough to know something was wrong. Rachel insisted on me making a doctor’s appointment and my doctor referred me to a consultant and, well, it turns out…’

‘What is it?’ I asked when she fell silent and lowered her eyes. My heart raced. I wasn’t sure I wanted to hear the answer. ‘What’s wrong, Mum?’

‘It’s Parkinson’s. I’ve got Parkinson’s.’

‘But…’ I paused for a moment, trying to digest what she’d just said. ‘But you can’t have. People with Parkinson’s shake. I’ve been around you all weekend and I haven’t seen you shaking once.’

She smiled weakly. ‘I said exactly the same to my doctor and to the specialist who diagnosed me. Apparently shaking’s one of the most common symptoms and it’s the one that most people associate with Parkinson’s, but it’s not the only symptom and some people don’t shake at all. The other main symptoms are slow movement and rigidity… or stiffness if you like. I’ve got that. It’s what makes me stop suddenly. I don’t shake, though. Some days I can move but not at a normal pace. I find that I can’t pick up my feet to walk properly so I shuffle along like an old lady instead. They’re my bad days.’

‘But I haven’t seen you suddenly stopping or shuffling.’

Mum’s eyes were full of sympathy as she watched me recall something that had seemed so insignificant earlier that day.

‘At the races today,’ I cried. ‘We were on our way to the bar. You were in front and you suddenly stopped and we all crashed into you. You said you’d spotted someone you knew but you hadn’t, had you?’

‘My feet wouldn’t move but how could I tell you that and ruin your day?’

‘Rachel manoeuvred us round you, joking that the last to the bar had to pay.’