Elizabeth Emmanuel, 64, was Diana’s wedding dress designer along with her now ex-husband David.
The team later went on to design a number of outfits for Princess Diana on her Gulf Tour.
In a new ITV documentary, Elizabeth explained the extreme measures she went to to prevent anyone discovering what Diana’s wedding dress was like.
She said on the programme that she refused to let any of the unused dress material be thrown away.
“I kept every scrap and we had to be very careful not to let any scraps fall on the floor because we didn’t want them to end up in the rubbish,” she said.
“We had a lot of journalists going through the rubbish to see what colour the dress was so I kept them pretty much as they were on the cutting table.
“Every thread was important as far as I was concerned,” she added.
The programme, Invitation To A Royal Wedding, will air on Sunday 29th April at 9pm on ITV.
Later on in the programme, Elizabeth spoke about her horror upon seeing Diana’s wedding dress had creased during the carriage ride.
She said: “We did know it would crease a bit but when I saw Diana arrive at St Pauls and we saw the creases I actually felt faint.
“I was horrified really because there was quite a lot of creasing there and she’s been in this little carriage with her father whose quite tall and she was all crunched in”.
The programme also touches upon a shocking joke played by Prince Harry on Kate and Prince William’s wedding day.
Harry caused a stir when he played a prank with the couple’s chocolate wedding cake.
It is said the royal, who will marry Meghan Markle, 36, on 19 May this year, played a practical joke on the wedding organisers on the special day.
It is known Kate and William had two wedding cakes on the special day: one fruit cake and one chocolate tiffin cake. Harry played a joke with the latter.
Master chocolatier Barry Colenso, who created Prince William and Kate Middleton’s second chocolate tiffin cake, explained what happened.
He recounted: “We’d just finished the cake, and I remember Harry came bounding in.
“Then he pretended to box with the top decoration. We were all like: “Oh no!”.
Thankfully, Prince Harry did not make contact with the cake, so a potential problem was avoided.