Daisy, aged 27, and husband Richard run horse sales and schooling business Exmoor Eventing, from where Madonna has bought a total of four horses.
Now, the singer has asked Daisy to spend two weeks coaching her at the FTI Winter Equestrian Festival, at the Palm Beach International Equestrian Centre, in Wellington, Florida.
Two of the four horses, all-rounder Boris and young eventer Sportsfield Silver Lining, have been flown to Florida and Madonna was expected to compete in the $50,000 Equisport Agency Grand Prix.
She said: “I picked out a bunch for her to try and she kept two on trial and decided to purchase them.
“Then she asked if I could go to her Wiltshire estate to help her get going on them and our relationship grew from there.
“Madonna and I just clicked. I took it all in my stride and I think she appreciated that.
“She wanted something nicely schooled and quiet, but she also likes to let the handbrake off, which does not always go hand-in-hand.
“So, we needed to find her a quiet horse with ability and a brain, too.
“They are not horses that are going to compete at the highest level, as this is not what she wants.
“She loves to jump, hack out, and hunt, and these guys fit the bill perfectly.
“If you work for her, you are in her friendship circle. I go for drinks and I went to her 50th birthday party and her latest gig at Wembley, where I sat next to Fergie, from the Black Eyed Peas, Naomi Campbell, and Gwyneth Paltrow, which was a bit surreal really.”
Since then, Daisy has continued teaching and riding out with Madonna, who has bought a further two young eventers from the Exmoor yard.
Daisy, who most recently rode out with Madonna on Boxing Day, said: “Teaching is not really my thing.
“I have always been a rider and I produce horses to sell, this is my love, but, when I have the time, I like to help those who want to be a better rider.
“When I teach her, I still tell her to put her heels down just like I would my Pony Club kids.
“She is very fit and supple, which helps, and she listens to everything you say.
“Being on tour, she has not ridden much lately and she wants me out there to help her get going again.”
Daisy said she had also learned a few lessons from Madonna during their sessions together.
“She is an amazing person who never moans about being tired, even with her hectic schedule,” said Daisy.
“Since meeting her, I have become more focused than ever.”
The only downside to the relationship was finding enough time to run the eventing business as well as riding and teaching.
“Madonna likes to ride at weekends but this is my busiest time competing, which is tough,” said Daisy.
“At times, I have been driving back and forth from an event to keep all sides happy.
“I am grateful for what she does for me as she supports me financially, which helps towards my eventing career.
“This year, I have given her my diary of events so we will see how that goes.”