She explained: "Three days before our wedding, we got married. No one knows that. We called the Archbishop and we said 'Look, this thing, this spectacle is for the world, but we want our union between us'. So the vows that we have in our room are just the two of us in our backyard with the Archbishop of Canterbury."
And Meghan admitted she was having an "out of body experience" on the day.
She added: "I've thought about this a lot because it was like having an out of body experience I was very present for.
"That's the only way I can describe it because the night before I slept through the night entirely, which in and of itself is a bit of a miracle.
"And then woke up and started listening to that song Going to the Chapel. And just tried to make it fun and light and remind ourselves that this was our day - but I think we were both really aware, even in advance of that just, this wasn't our day.
"This was the day that was planned for the world."
Borton, now a consultant for the Faculty Office, said: "They couldn't have got married in the grounds of Nottingham Cottage as it is not an authorised venue and there were not enough witnesses present.
"You cannot be married with just three people. It's not a valid ceremony.
"I think the Duchess is confused. Any certificate she may have of her vows on the wall is not an official wedding certificate.
"The wedding itself took place at St George's Chapel under the conditions stipulated by the Royal Marriages Act of 1772 which have been recently amended.
"In order for them to be married a Special Licence was drawn up and the wording from Her Majesty the Queen authorising the wedding and the official venue was recorded."