‘The last owner who tried to ride his own horse got tanked,’ said the trainer, looking up at me as I perched on Darcy, knees nearly up to my chest like a pixie in the racing saddle.

‘After three circuits he threw himself off into the muck heap.’

‘I get the picture,’ I said, running my gloved hand against Darcy’s neck. ‘Please, look after your mother,’ I whispered to her. She was perfectly calm beneath me. Because I raised her, I have always felt like I can trust this horse with my life. I was about to find out exactly what that meant.

It is all very well trusting a horse you have raised from a yearling while cantering her around the woods. It is quite another when that thoroughbred has grown into a gleaming racehorse.

Suddenly, at that point, a thought comes into your head that you believe you have invented and that no owner before you has ever had: ‘I know! I am going to ride my own racehorse! I am going to be like Elizabeth Taylor galloping The Pie to victory!’

I told the trainer of my plans. The trainer is a veteran jockey who has seen people like me come and go. It turns out I am not the first person since Velvet Brown to think of riding her own racehorse. He has seen lots of women like me take leave of their senses, and the odd City boy too.

His response was far more accommodating than I had expected. No doubt he has discovered that the best way to disavow an owner of the notion that they can become the next Frankie Dettori is to let them climb aboard.

He agreed I should join them at 10 a.m., for the last ride out. When I arrived, he greeted me with his arm in a sling and a huge cut above his left eye, still bleeding.

‘My god, what have you done?’ I asked. ‘Oh this?’ he said, absent-mindedly. ‘Shoulder got pulled out again. Pushed it back in myself.’

I took the precaution of packing myself into a back protector. The look wasn’t quite as stylish as Liz Taylor but I could work up a pair of white breeches and a snazzy silk top. Darcy was led out to the mounting block and up I went. Perched like a pixie, I followed three jockeys out of the yard.

As we hacked into the common for a warm-up, the female jockey in front turned to give me a tip. ‘You’ll find it easier if you put your stirrups up,’ she said.

‘Up? I don’t think I can get my legs any more bent than this.’

As we approached the gallops she turned round again. ‘When you see the shed coming round for the second time start pulling up, OK?’ I nodded. ‘We’re going to help you out. Try to stay at the back but if something goes wrong and you need to pass, shout out.’

I nodded. Then I leaned forward and whispered again to my girl. ‘You need to look after me.’ Darcy was inscrutable. Calm as you like, and totally self-possessed. As soon as we were on the red sand, the girl called out to see if I was ready and when I shouted back ‘yes’ something happened that I cannot quite describe.

I have been riding horses since I was four years old. I have galloped more times than I can count. But by gallop, I mean gallop normally, on a normal horse. Not a thoroughbred a few removed from the great Nijinsky.

What happened when we took off on those gallops will go down as one of the greatest experiences of my life. I have never felt anything like it. Darcy went upwards as if spring-loaded and then forwards at a speed I could not fathom. I swear, I felt the engine roar. She took me round that track so fast and furious I felt like I was riding on the back of thunder. Who says man cannot fly?

The stirrups weren’t quite short enough. And my 43-year-old legs need some toughening up. The athleticism required to be a jockey is just staggering. It was all I could do to force myself, second by second, against all rules of gravity, to stay on. If my legs gave way, I was going to fall out the side at 40mph.

As fast as we were going, time slowed down so that the circuit and a half felt like it went on for ever. And even though my legs wouldn’t have held me on for much longer, I never wanted it to end.

When I got home I sat on the sofa and thought, ‘I will never be the same.’ I am counting the hours until I get to fly again.