The smile on Jeremy Vine's face is freighted with sadness as he recalls the time he tried to teach his newly retired father, Guy, how to cook.
The radio and TV broadcaster not only wanted to extend Guy's kitchen repertoire (since it only stretched as far as 'a decent fried egg'), but it would also be, he thought, a lovely way for father and son to spend time together.
Yet the memory of this culinary venture in 2010 is bittersweet. For it gave Jeremy the first clue that his father, an otherwise fit 72‑year-old Cambridge graduate who'd never been ill in his life, was declining due to Parkinson's disease.
This progressive disorder of the nervous system affects 145,000 Britons each year. Last month, singer Ozzy Osbourne announced he had it, too.
And just last week research suggested that people who develop Parkinson's before the age of 50 may have been born with it.
Close bond: Jeremy and his beloved father, Guy. Jeremy's father was 72 when he began to decline due to Parkinson's disease
A major issue for patients, as the Vine family discovered, is that Parkinson's can take years to diagnose, since it is difficult to identify.
Symptoms can easily be put down to other problems. Some sufferers will experience tremors or instability and tense muscles; others develop changes in speech, anxiety, digestive problems, insomnia and memory loss.
Jeremy noticed warning signs that time he was in the kitchen with his father. As he explains: 'I was teaching Dad to cut onions, and yet he couldn't do it with any power. The knife kept slipping, he couldn't hold it firmly.
'Of course, being Dad, he just laughed it off. But something told me he wasn't OK.
'Dad had always been fit, he played squash and there wasn't a spare pound of flesh on him. He also had an incredibly lively mind — a man who loved reading about engineering, and, as a mathematician, was especially fascinated by prime numbers.
'Yet, suddenly, he couldn't use a kitchen knife properly,' recalls Jeremy, 54, who lives in West London with wife Rachel, 44, a journalist, and their two daughters.
With no known family history of Parkinson's, the Vine family — including Jeremy's mother Diana, a former doctor's receptionist, and his siblings, the comedian Tim Vine and sister Sonya, an actress — were puzzled by Guy's decline.
With no known family history of Parkinson's, the Vine family — including Jeremy's mother Diana, a former doctor's receptionist, and his siblings, the comedian Tim Vine and sister Sonya, an actress — were puzzled by Guy's decline
'Soon after that episode in the kitchen I began to notice Dad's voice started getting quieter,' says Jeremy, sadly.
'He began shuffling and dragging his heels. Even his vocabulary started to shrink. I remember talking to him about something that had upset me, and I'd expected a comforting response. Yet he seemed to struggle to say the right words, which was very disturbing and upsetting.'
Eventually, in 2014, as Guy's symptoms gathered pace, Diana took her husband to the doctor. Observing his trudging gait, the GP immediately pronounced that Guy had Parkinson's. A referral to a neurologist confirmed it.
'When you hear the diagnosis, a penny drops,' says Jeremy, who presents daily shows on Radio 2 and Channel 5. 'We finally realised that Dad's turbo-charged ageing had a cause.
'But learning about how Parkinson's would progress was very difficult for us all to deal with. We were told, in Dad's case, it was mild, but that it is impossible to predict.'
Parkinson's can vary in severity from one patient to another and accelerate at different rates. This depends on the number of brain cells affected by the disease. It is characterised by low levels of dopamine — a brain chemical that sends signals between nerve cells and helps to coordinate muscle movements.
The cause is unclear, though researchers believe it is due to a combination of genetic and environmental factors (there is speculation of a link between the use of pesticides and Parkinson's, for example) that causes the dopamine-producing nerve cells to die.
Even now, Jeremy (pictured) shudders as he remembers his father's emaciated appearance; the man he loved so much fading before him
The lack of dopamine