Diana's memorial to get million pound facelift in time for 20th annivesary of her death

Princess Diana's final resting place at Althorp is to be revamped in time for the 20th anniversary of her death next year. Photo / File

The island where Diana, Princess of Wales is buried is to receive a multi-million facelift as part of the Spencer family estate gardens' first major revamp in 350 years.

A statement on the Althorp website describes the "ambitious" project, which will be overseen by Earl Spencer's third wife, Lady Karen, whom he married in 2011.

It will include an "extensive redesign" of the Oval Lake, where she was laid to rest in 1997, to "honour her memory".

It follows criticisms from her former personal chef, Darren McGrady, that her burial place had become neglected.

Think this is good enough for Prince William and Harry's mother ? #CleanTheLake #Althorp #PrincessDianasRestingPlace pic.twitter.com/rYIYQk8PXS

— Darren McGrady (@DarrenMcGrady) August 19, 2014

He visited the 500-year-old estate, which has been home to the Spencer family for 18 generations, in August 2014, and posted a number of pictures of a moss-covered memorial to the princess on Twitter.

He also wrote: "Sad to see Earl Spencer has neglected Diana's resting place. "Please tidy up the vegetation on the island".

A spokesman for Althorp said the grave was swathed in flowers and foliage because it had become "part of the ancient landscape over time" and that it was intended to "lend privacy to the Princess's final resting place".

The precise location of Diana's grave has never been made public, and visitors paying up to £18.50 to enter the estate are not permitted on the island.

She first moved to the family's ancestral seat in Lincolnshire in 1975, after her father John Spencer inherited the title Earl Spencer.

Image 1 of 12: Prince Charles and Princess Diana With The Newly Born Prince Harry Outside The Lindo Wing. Photo / Getty Images

It has been overseen by her younger brother Charles, the ninth Earl Spencer, since her father's death in 1992, and features 38 specially planted oak trees - one for each year of her life.

Work to substantially remodel the island will be completed in time for the 20th anniversary of Diana's death, in August 2017.

It is part of a process which will see the 5260 hectare estate's gardens transformed over the next 18 months, and coincides with the opening of a new memorial garden at Kensington Palace alongside an exhibition on former Princess of Wales' life.

Last week Prince Harry, 31, said his mother's death had left a "gaping hole" in his life.

He added: "All I want to do is make my mother incredibly proud."