"I didn't think I would be nervous, I must admit, because we've done some things with some very eminent people in the past, but as soon as she walked in the room, I remember my throat just caught. So it was quite an experience," he said.
The sculptor led a dedicated team of 20 people for more than four months to create the new figure, which cost 150,000 pounds ($NZ310,000) to make, as part of Madame Tussauds' plans to celebrate Elizabeth's diamond jubilee this year.
"Our guests come from all over the world, and she is the most photographed wax figure, she is the person that people come and see. It's such an exciting year in London this year and we want to be part of that celebration," Madame Tussauds spokeswoman Liz Edwards said.
Dressed in a white and silver lace dress, embellished with 53,000 Swarovski crystals, and a blue silk sash, the wax figure of the queen is a commanding presence, despite stiff competition from pop stars Rihanna and Lady Gaga in the same room.
Madame Tussauds has been making wax figures of Elizabeth since she was two years old and the latest version is expected to steal some of the limelight away from the figures of her grandson Prince William and wife Catherine, the Duchess of Cambridge, whose fans have flocked to the attraction.
Swales said he adjusted the latest figure's posture slightly from the last one he created for the Golden Jubilee to make her appear more welcoming to the public.
"I think that the Royal family are a lot more accessible than years ago, when I was very small, you might see them going past in a car or something like this, but now I think people have taken her to their hearts really."
"She's an amazing professional, very, very nice and I just think she's just such a patient person. It's amazing working with someone like that."