THE LAST time best-selling novelist Valerie Blumenthal drove her car, she went to the supermarket.

She saw a nice, big, open parking space and started happily reversing into it.

Just in time, she realised she wasn’t reversing into an empty space at all, but into the car parked next to it, and slammed on the brakes.

It’s just one example of how an unusual form of early-onset Alzheimer’s disease has affected her life.

Mrs Blumenthal, who has published eight novels including the best-seller Saturday’s Child, was diagnosed with posterior cortical atrophy (PCA) 18 months ago, while still in her late 50s.

It’s the same form of Alzheimer’s from which another famous author, the late Terry Pratchett, suffered , attacking the rear part of the brain responsible for visual function, rather than the front, which affects cognitive function.

For Mrs Blumenthal, who lives with her husband Chris in the village of Moreton near Thame, it means she can see everything, she just can’t process it.

“The worst thing was my wing mirrors,” she says, in a jolly-hockey-sticks manner.

“I clipped them so much I had to get about seven new mirrors – that’s how close I was to killing someone.”

Thankfully for the rest of the driving population, Mrs Blumenthal does not drive any more.

Sadly for her, it is just one of the many activities she used to love which PCA has torn away from her: riding, painting, playing the piano, even walking downstairs without thinking about it are all now inaccessible to her.

Eventually the disease will spread to the rest of her brain.

“There’s nothing you can do about the future,” she shrugs pacifically, “the things I can’t do, I don’t focus on.

“My husband bought me a wonderful set of paints for my birthday, so I’m now going to do abstract painting.”

Once a passionate and accomplished pianist, she can no longer play the pieces she loves, so instead she improvises.

One thing, however, that she very much still can do is sing. A trained operatic singer, she still has regular lessons.

And so it was singing that she chose as the main activity for an event to raise funds and awareness for Alzheimer’s in her village next month.

Mrs Blumenthal, mother to one grown-up daughter, is hoping to get just under 100 people, paying £10 each, to squeeze into an old barn in the village from 11am on Saturday, September 5, and sing the roof off.

The programme will be a slew of good old-fashioned singalongs from When The Saints Go Marching In to Those Were The Days.

And she makes it very clear, no one is invited to simply come and watch: “They’re all jolly well going to sing.”

The event will raise money for two charities – Alzheimer’s Research UK and the Witney-based Young Dementia UK.

About 80 people have already signed up, but Mrs Blumenthal said she could probably squeeze a few more in.

For more information call her on 07786 057904.

The other thing she can still do, somewhat surprisingly, is write, and after five years she has just completed her latest novel, The Lupo Stick, she hopes will be published in the UK soon.