A rare glimpse into Princess Diana's day at royal wedding

The 1981 wedding of Prince Charles and Lady Diana Spencer set the standard for modern royal weddings. Thirty-four years later, a collection of 12 candid photos from that day is going up for auction.

They offer a rare glimpse behind those closed doors after the wedding of the last century, reports CBS News correspondent Charlie D'Agata.

The young bride cuddles and comforts her youngest bridesmaid with the queen by her side.

The new princess, barely 20 years old, inside the palace she believed would one day be her home.

The dozen candid photographs were shot by an assistant to the official royal photographer, Lord Lichfield, a flamboyant friend of the queen and the only cameraman given exclusive access behind the scenes that day.

"I'm rather like the bad fairy at a wedding. The photographer is the one person that is basically holding up the events of the day for, at the time, a seemingly rather unimportant process, which later will be important," Lichfield said in an interview with CBS News in 1981 ahead of the big event.

The photos up for auction were the ones that didn't make the cut in the official wedding album presented to the Royal Family -- shot from behind, Diana with Charles by her side or the newlyweds' view from the balcony of Buckingham Palace, greeting thousands of well-wishers.

And did you ever wonder whether the queen herself watched coverage of big events on a small TV?

The private reception was thrown after the royal wedding ceremony at St Paul's Cathedral, watched by an estimated TV audience of 750 million people at the time, and more than half of the photos show Diana in her silk and taffeta wedding gown, with its 25-foot train.

Not only previously unseen, they show the unguarded moments rarely seen at all, says royal correspondent Roya Nikkhah. She said the viewer feels like she or he is there because the images are behind the scenes.

"You can see how ... the assistant is trying to get these very off-guard moments of the queen watching the coverage on TV and Diana scooping up her dress with a bridesmaid in her arm. ... Those images are rare. She became so much savvier with the media as things went on. This is still Diana, very young, not quite so savvy with cameras around her," Nikkhah said.

The entire set goes under the hammer next month. The minimum price is set at $300, but auction organizers said they're expecting bids somewhere in the neighborhood of $20,000.