A picture of health: Angelina Jolie and fiancée Brad Pitt make first public appearance since double mastectomy news at World War Z London premiere

Angelina Jolie made her first public appearance last night after revealing in May that she had undergone a preventative double mastectomy.

Appearing on the red carpet for the premier of fiancée Brad Pitt’s new film World War Z, Jolie wore a black gown by Saint Laurent and told reporters: “I feel great. I feel wonderful”

Both Pitt and Jolie looked emotional as they spoke about the recent operation and met with fans, many of whom who had brought signs showing their support for the 37-year-old mother of six.

Jolie spent twenty minutes amongst the crowds, signing autographs and snapping pictures. She said that she had been “grateful and moved” by the public’s reaction to the news and also thanked Pitt.

"He's been extraordinary," said Jolie.  "He's such a wonderful man and a wonderful father and I'm very, very lucky.

"I'm very happy just to see the discussion about women's health expand and that means the world to me. After losing my mom to these issues, I'm very grateful for it, and I've been very moved by the support from people. I'm really very grateful for it."

Pitt, 49, spoke of the difficulty that the couple faced, and was close to tears as he detailed the “heroism” of his fiancée: “As the other half, when you’re sitting and waiting it’s emotional. But I got the easy part.”

 “I’m very proud and I’m just relieved that’s not going to be the thing that takes her out. The biggest fear as a father is keeping the family alive, safe and together — she did that. I’m getting a bit teary-eyed thinking about it.”

Jolie had opted to have the double mastectomy after finding out she carried a faulty gene, named BRCA1, which meant that her likelihood of developing breast cancer was 87%. The operation meant that those odds dropped to just 5%.

The Tomb-raider star’s mother, Marcheline Bertrand, died of ovarian cancer in 2007 – another disease that is associated with the faulty gene.

Her aunt Debbie Martin also died of breast cancer a week ago, with Jolie missing the funeral in order to be at last night’s premiere.

World War Z, which is released on June 21, starts Pitt as Gerry Lane, a UN employee who travels the globe to try and stop a zombie pandemic that is destroying civilization.