An unwashed sweatshirt once worn by Diana, Princess of Wales during exercise sessions has been sold at auction.

Boston-based RR Auction said the piece of clothing went for 53,532 dollars (£42,739) after bidding concluded on Wednesday.

It was put up for sale by Diana’s former personal trainer Jenni Rivett, who plans to donate the proceeds to help a Malawian family in South Africa, where she is from.

British entrepreneur Sir Richard Branson originally gave the princess the dark blue medium-large, cotton-polyester sweatshirt, which features a screen-printed image of the Virgin Atlantic flying lady logo.

Diana gifted the item of clothing to Ms Rivett with a signed note that read: “Dearest Jenni, Lots of love from, Diana, x.”

In one of two letters of provenance accompanying the sweatshirt Ms Rivett wrote: “This sweatshirt was given to HRH by Sir Richard Branson.

“It became her most worn top on her regular visits to the gym.

“She felt there were far more important issues to focus on in the world than her gym attire and therefore decided that wearing the famous Virgin sweatshirt to every session, would be a good way to stop the media frenzy!

“A few months before her untimely death, she called me to say she had left a few sweatshirts for me.

“Amongst them, this one — which I have now decided to part with to help a Malawian family in South Africa.”

The other letter stated: “This sweatshirt given to Princess Diana by Sir Richard Branson has never been washed!”

The winning bid was made by a collector based in California who chose to remain anonymous.