The last letter Princess Diana wrote before her tragic car crash in 1997 is set to sell at Fellows on April 28 in the UK.

The letter is written on Kensington Palace headed paper

Consigned to auction by a private collector, the letter was written on August 11, 1997, 20 days before the princess was killed in Paris - an event mourned across the world.

Estimated to sell for £2,000-3,000 ($3,359-5,039), we believe the letter should comfortably surpass its valuation, not only because it is Diana's final correspondence, but also for its connection to her charity work, which contributes to her continuing popularity among collectors today.

The letter was purchased in 2007 from Jason Fraser, a celebrity photographer who had known Diana personally, who in turn had bought it from the addressee, Dilys Cheetham.

Diana sent the letter, which is full of her famous charitable nature, following a trip to Bosnia where she met with those affected by landmines.

The princess writes: "I could not help but be deeply moved by the experience which hardened my resolve to ensure that the world does not forget that those who have been so needlessly maimed by these terrible weapons will need care and support for many years to come."

Princess Diana's memorabilia is some of the most sought after on the collecting market, with the dress she wore while dancing with John Travolta at the White House selling for $362,500 at auction in 2013.

Paul Fraser Collectibles has a fantastic selection of Princess Diana items for sale, including a rare slice of her wedding cake.