A former flatmate of Diana Princess of Wales has said she “picked up many people’s lives”, as a blue plaque was unveiled in her honour.

The memorial was installed at the princess’s old flat at 60 Coleherne Court, a property in a mansion block close to the fashionable King’s Road in Chelsea, where she settled as a young woman before marrying the Prince of Wales in 1981.

She shared the flat with a number of girlfriends from 1979 to 1981 including Virginia Clarke (nee Pitman), who unveiled the English Heritage plaque during a ceremony on Wednesday.

Diana described her years at the property as “the happiest time of her life”, according to Andrew Morton’s book Diana, In Her Own Words.

Speaking to the PA news agency after unveiling the plaque, Ms Clarke said: “As I mentioned in my speech, Diana and I had actually driven around London talking about blue plaques, so I knew that she would have really liked it.

“Also, because there has been a lot of quite negative press about her, I just thought it’s so nice to be able to come and celebrate the good times – I know that she was happy here.”

Asked to put into words the contributions made by Diana in her life, Ms Clarke said: “She has done a lot. She was terribly good at remembering everybody and speaking to people one-to-one, and I think she really picked up many people’s lives all around the place wherever she travelled and just made them feel better.

“I know there’s a lot of talk about her charities, and that was all wonderful, but just on a one-to-one basis, she was terribly good at that.”

The highest profile former member of the monarchy to be bestowed the honour, Diana was nominated by the London Assembly after it ran a campaign asking Londoners to suggest women worthy of a blue plaque.

She is being recognised during a year when she would have celebrated her 60th birthday. She died in a Paris car crash in 1997.

Questioned on how she felt when she was asked to unveil the plaque, Ms Clarke told PA: “Initially I was nervous because I am slightly suspicious of the press.

“But then I thought that was years ago, get over it and do something that would be fun and different and positive.

“I felt slightly nervous but then I thought, I’m an old woman now and life has moved on and I’ve got children who are older than I was then – so I just thought ‘let’s do this’.”

Ms Clarke gave a short speech to a small crowd outside the flat where she said it was “great to cherish this place in her name”.

Commenting on how it feels to have a blue plaque where she used to live, she added: “I was saying to one of my children, when I’m dead and gone, you will drive past that plaque and know that I pulled the string.

“It makes me feel really nice – it’s really a big thing.

“Even though my name’s not on there and it’s not really for me, obviously, I still feel it’s a lovely thing to have here.”

Speaking ahead of the unveiling ceremony, curatorial director at English Heritage, Anna Eavis, told PA: “Diana was one of the world’s most famous women and she used her fame and influence to raise awareness of issues such as homelessness and landmines.

“She played a critically important role in helping to destigmatise illnesses such as HIV, leprosy and depression.

“We don’t often give plaques to members of the royal family because they are commemorated so comprehensively elsewhere, so it is very unusual.

“It is fitting that our blue plaque remembers her at this place where her life in the public eye first began.”

Andrew Boff, chairman of the London Assembly, said: “The London Assembly BackthePlaque campaign in 2019 had a wonderful response and provided some fascinating nominations.

“We understand why many thought the work of Diana, Princess of Wales should be recognised – her landmine campaign and HIV/Aids awareness work was truly global and made an enormous difference to many lives.

“Diana had, and still has, a very special place in the hearts of Londoners and we are thrilled to see her blue plaque formally placed as a monument to her work for others.”