When you've watched her acting in so many iconic film roles (Lucinda Leplastrier in Oscar and Lucinda, Meredith Logue in The Talented Mr Ripley, Elizabeth Tudor in Elizabeth, Jasmine French in Blue Jasmine, or Katharine Hepburn in The Aviator), it is almost unnerving when you are ushered into a big suite and Cate Blanchett is just sitting there ... playing herself.
She is not the austere, aloof Hollywood movie star one might expect. Warm, normal and above all friendly, she wears her superstar status lightly. She is wearing a Giorgio Armani New Normal grey suit. At the cocktail party later that night, she wears a powder-pink Giorgio Armani sleeveless dress.
The globally feted Italian fashion titan is the reason Cate is in London today - to attend the unveiling of Armani's Si Le Parfum and the Si Women's Circle, which is described as "a newly created digital platform that encourages open dialogue between one another and serves as an opportunity to share life stories". Cate has been the face and ambassador of Armani's fragrance Si for three years.
I ask Cate what drew her to Giorgio. "He has been a huge aesthetic influence on my sense of what was possible, visually, as a woman when I was at school," says Ms Blanchett, who was born on May 14, 1969 in Melbourne, Australia.
"My jaw hit the floor when I first started seeing his now iconic and much absorbed influence of masculine and feminine tailoring. So I tried to emulate that in an second-hand way, until finally, when I got my first pay cheque from my first theatre job, I went to a sale at the Sydney store - and I bought a Giorgio Armani suit."
Asked how much her first pay cheque was made out for, the actress, who is now on quite a few million dollars per picture laughs, and says, "Oh, it was about 25 cents!
"That was my entire pay cheque for the whole season! So it wasn't particularly sensible, but I'd always wanted one. I still have the suit. And that's the thing - his design, his aesthetic, is timeless."
When she describes Giorgio Armani's personality as "intensely curious, intensely singular," Cate Blanchett could be describing herself, too.
"He is so difficult to catch," she continues. "I think he is a bit like Santa Claus. Apparently, he was here last night and I missed him; I was staggering to get up to finish the school run," she jokes, referring to her children - sons Dashiell (14), Roman (12) and Ignatius (7), and toddler daughter Edith, whom she and her husband, playwright Andrew Upton, adopted in March 2015.
Cate Blanchett has been nominated six times for an Academy Award: she's won two - for 2004's The Aviator and 2013's Blue Jasmine. Yet, wriggling way inside her soul, is the worm of self-doubt and fear ...
Todd Haynes (who directed her as Bob Dylan in 2007's I'm Not There and more recently in 2015 as lesbian New Yorker Carol in Carol) told Variety in 2015: "There are days when she's frustrated by her own work. We don't know what she's talking about, but she'll say, 'I need to take an acting pill today. It's not working'."
I ask if it's true she was "disappointed" when she watched back her performance in The Aviator. "I am filled with regret whenever I watch anything I do, which is why I tend not to watch them."
To illustrate how women find their voice, Giorgio Armani chose various women with different stories to be part of the new Si campaign and show how they said Si (yes) to their dreams. Among them, is Kee-Yoon Kim (a lawyer in Paris, born in Berlin to Korean parents, who decided one day she wanted to be a comedian); Cecile Schmollgruber (from San Franciso, she is the founder of 3D tech brand Stereolabs); and Charlotte Ranson (an inspirational coryphee - leading dancer with the corps de ballet - with the Paris Opera Ballet).
"The three women that I've met so far, Cecile, Charlotte and Kee-Yoon Kim, their experiences have been so different," Cate says, "but their stories are really inspiring. There is a commonality there, even though we're working across very different disciplines. Women are very good networkers, naturally. The more those stories are shared, the more you realise that there are points of connection....
"I think it is really important that those stories are shared, because they are inspiring and edifying. Because no matter where you are in your career, if you are going to continue to have a fruitful and eventful career - I don't necessarily mean a so-called successful career, but eventful and challenging - then you are going to come across hurdles and pitfalls."
When you started out, was there a moment when you said: I'm going to push through this difficult time?
"I think it happens every second Wednesday," says the Wizard of Oz, with perfect comic timing.
Last month, Cate was appointed goodwill ambassador for the UN Refugee Agency (UNHCR). Being a global ambassador in relation to refugees is a somewhat different role to being an ambassador for Armani.
"My dance-card has been very full of late. You know - running a theatre company, having four kids - and now that I'm not running the theatre company," Cate says in reference to the Sydney Theatre Company that she and her husband Andrew had been running together since 2008, "I feel issues that have been plaguing and distressing me need to be discussed in an intelligent, humane way.
"And I can finally have some space to lend my voice to giving people access to the human stories that are behind these overwhelming numbers: 16 million people displaced. It is incomprehensible. More than since the Second World War. You feel disempowered.
"So when the UNHCR approached me, I jumped at the opportunity. It was a huge responsibility and a privilege, but it was also a chance to try redress the balance of this distressing xenophobia that is creeping into the parlance in relation to refugees - not just here, but in my country of birth."
Running a theatre company, being a mother, being a movie star, being an ambassador to Armani, UNHCR, etc ... how does she manage?
"I don't manage at all. Ever! Chaos!"
What drew her to the role of Irish crime reporter Veronica Guerin, whose life was taken in cold blood, in broad daylight, on June 26, 1996, and whom Cate played in the movie of that name in 2003?
"I found the Ireland that one experiences in literature and in picture-postcards is not the Ireland that Veronica Guerin dealt with, and so I found it revelatory that she was co-existing in [what was] once a village, but also in this terrible, complex morass of this underworld that had a much broader reach than beyond Irish shores," Cate says.
"What I found perplexing was that the questions that I got asked when we did the publicity was 'How do you feel about what Veronica did as a mother; how could she do that as a mother?'
"You think - what she was doing was profoundly important, and she was chasing a story the way any good male investigative journalist was doing it.
"So I think she was groundbreaking, not only in what she achieved in her very short lifetime, but also groundbreaking as a woman. You do think that it is 20 years now, and that those questions are still being asked of war correspondents.
"I think when the word 'journalist' is being bandied around by a lot of people who probably aren't journalists, I think Veronica really holds a candle to why journalists get into it in the first place, that is to uncover something, a story that needs to be told."