Anne said she was on the way to see chickens on her estate when the accident happened but has no memory of what followed.
Shortly before her transfer to the hospital, emergency services and an air ambulance rushed on-site to administer medical care.
Following her five-night hospital stay, the princess spent three weeks recuperating at home before returning to public duties.
Now, a source has said that despite Anne, who was back on riding for the first time in public during Trooping the Colour this June, getting back to being her usual, hard-working self, the incident was worse than what the public were led to believe.
The source, who is said to be close to the princess, told The Times: "Her accident was so much worse than anyone let on and it took quite a while for her to feel herself again."
Anne said: "You're jolly lucky... if you can continue to be more or less compos mentis and last summer I was very close to not being. Take each day as it comes, they say.
"You are sharply reminded that every day is a bonus really."