Several letters that Princess Diana wrote to her former nanny, including one comparing her own dancing skills to those of an elephant, will be auctioned in London next week, and they are expected to sell for thousands of dollars.

Diana once famously danced with American actor John Travolta at the White House. But as a teenager, she wrote in a 1978 letter to her former nanny that she loved dancing but that, "Watching me dance is like watching an elephant, so no one does!"

James Grinter, an auctioneer with Reeman Dansie, the house selling the four letters and two cards next week, said Tuesday he expects them to go for up to $18,000.

One of the letters to the former nanny, Mary Clarke, was written a few years before Diana married Prince Charles in 1981. In it, Diana said she had briefly considered the prince as a possibly suitable mate for her older sister, Sarah.

Diana wrote another letter during her engagement to Prince Charles. "Not too long to go now and about time too! Six months of being engaged is quite something and definitely to be avoided! All the family in complete overdrive and a lot of non speaks going on!" Diana wrote.

Princess Diana, her friend Dodi Fayed and their driver died in a car crash in Paris in 1997.

The auction house also is selling a 1937 letter that American socialite Wallis Simpson wrote to a cousin while on a honeymoon with King Edward VIII.

In it, Simpson writes, "Here I am at last with my king, sitting on a mountain in Austria, where it is really lovely and peaceful. We hope here to gather strength for future battles."