Pippa Middleton at the Royal Wedding

Pippa Middleton at the Royal Wedding

Britain's Pippa Middleton has joked her infamous bridesmaids dress "fitted a little too well".

Duchess Catherine's younger sister became a worldwide sensation in April 2011 when her pert rear in her cream Alexander McQueen bridemaids dress stole the show at Kate and Prince William's wedding in London's Westminster Abbey.

Pippa has finally opened up about the figure-hugging gown, joking in a speech at the Women in Advertising and Communications dinner: "As I have found out, recognition has its upside, its downside and - you may say - its backside."

The brunette addressed a crowd of 400 at the event at Central London's Savoy Hotel, where tickets cost a whopping £132, admitting she didn't sleep for two nights before the landmark televised wedding because she was so nervous.

She said she was "glad [the dress] fitted" at the time, adding, "In retrospect it fitted a little too well".

A guest told the Daily Mirror newspaper: "It was the first time she's made a speech of this kind but you wouldn't have known it, she was so relaxed. It was unbelievable how open she was - I don't think anyone was expecting that.

"She talked about the royal wedding and her career since. She came across as really grateful for the opportunities but also talked about the pitfalls of her position."

The 30-year-old beauty also confessed she was hurt by allegations she was cashing in on her sister's connections by writing her party-planning book, 'Celebrate'.