Caitlyn Jenner was housebound for three months during her transition into a woman

Caitlyn said: "I've basically been inside this house for the last three months. I haven't really left. It's difficult because I can't go out and be seen by the paparazzi, they're literally sitting down there.

"I would wear sweatshirt with hoods on them. And if my fingernails were polished - it was just hell. ... It was really, really tough on me."

Security was so tight that photographs and interview notes from inside the house were uploaded to a computer that was disconnected from the internet at all times. When the final piece was ready, the files were hand-delivered to the printers by Vanity Fair's associate managing editor, Ellen Kiell.

In the 10-minute documentary - posted by the magazine on Vanity Fair's website - Caitlyn's reaction to her new look is caught on camera.

She says: "Honestly, I think we accomplished a lot of things today. They put this mirror up behind me when I was doing the shoot, I had this rocking black outfit on, ... and I kind of from a distance looked in the mirror and I go, 'Oh my god. It's the first time I'd ever really seen an image of me - of who I am - I mean.

"I kind of looked down and said 'You know what, this is going to work. We're going to be OK with this.' So yeah, we move forward. I am so excited about the future."