"Rare" portrait of Princess Diana goes on public display for the first time in honour of her 61st birthday

Following what would have been her 61st birthday, a rare portrait of Princess Diana will be on public display for the first time after it was recently sold at auction.

The oil painting was completed by artist Nelson Shanks in 1994 - three years before Diana's tragic death - and will be featured in Philip Mould & Company's gallery in London.

In the artwork, Diana is shown wearing a green velvet Catherine Walker halter dress that she wore in the lead-up to her famous 1997 Vanity Fair magazine shoot.

Unusually for a royal portrait, it captures the princess looking pensively down at the floor, with a single earring providing a sparkle of light.

The People's Princess sat for more than 30 sittings at Shanks' studio in London to capture the image, which served as a preparatory study for a formal full-length portrait.

The portrait made headlines in January when it was sold at a Sotheby's auction for $201,600 - more than ten times its original estimate.

It was originally displayed at the Kensington Palace home Diana shared with sons Prince William, 40, and Prince Harry, 37, before it was later moved to her family estate at Althorp House in Northamptonshire.

The beloved princess died at the age of 36 when the car she was travelling in crashed in a Paris tunnel on August 31, 1997.

William and Harry were just 15 and 12 at the time.