And Tori Amos has been hiding in the wings, and beetling backstage, and peering anxiously from the gods – the American-born, Cornwall-based singer-songwriter spent much of 2013 co-creating The Light Princess, a musical staged in partnership with London’s National Theatre.

She needed, she concedes now, to escape – from her past, from the norm, from her well-established musical career path.

“After 2009 I walked into three records that are sort of a period of writing that was a different stylistic choice,” says Amos. “I needed to walk away from contemporary songwriting. I needed to do something different as a writer. And I remember being on tour in Poland in 2009, and looking up to the muses and saying: ‘I have got to do something different!’” she laughs. “Because I felt like I had pushed it to the envelope of my abilities – meaning, the envelope of my intelligence! I was on the edge! I was skating! I couldn’t create any more in the same way.”

But those three diverse album projects, followed by her first full-bore theatrical project, alchemised something anew within. Out of the flux of ambition and distraction and imagination came Tori Amos’s 14^th studio album: Unrepentant Geraldines.

“Women would talk to me about feeling trapped, which is explored a lot in this record – there’s a freedom I had writing this record. But I could only have that freedom because of the other three projects and doing The Light Princess – writing for other voices, other people, other artists. Working with an orchestra, with an octet, a Polish quartet… I’ve worked with hundreds of people in the last three or four years. Which is kinda crazy!” she smiles. “When you think about the National Theatre, that’s like an army of stage people that you get to collaborate with on a daily basis.”

That energy is focused, centralised and concentrated on the vivid and vital Unrepentant Geraldines. It’s an album on which Amos once more zeroes in on the writing of brightly melodic, deftly evocative chamber-pop. Fairy-tale soul-poems, you might say.

“I turned 50 this year –and certain people really helped me to see it in a different way and grab it with both hands. The song 16 Shades Of Blue talks about ageing from many points of view. And as I started to dive into it, I started to learn from all women of ages that age was a difficult thing for them – whether you’re talking to a 15-year-old who feels pressure to choose their career path for life or a 33-year-old who fears she won’t get the promotion if it is known that she is planning a family. They all felt the pressures in the ageing process.”

That discovery was followed by another, one that spoke to Amos both as a lifelong art lover and as a writer with a sharp new perspective on life. It would give her the title for her new album.

“I discovered Cezanne this past year. And I just never got it before. All my life I have been going to art and artists to hear. One day I was looking through a book and I started hearing when I stumbled upon Cezanne’s “The Black Clock”. He was known to have at least 16 Shades of Blue as part of his colour palette.

Last year I discovered an etching by Daniel Maclise, who was a 19^th century Irish artist of a penitent woman called “Geraldine”. A painter friend of mine showed it to me. He told me I needed to have this painting on my wall. When I saw it, it reminded me of the Repentant Magdalene paintings of Seghers, de la Tour and Titian and what women have had to go through, over the centuries and how women’s sexuality has been judged and shamed.

“I began thinking about religion and the world and the 21^st century, and if most women can honestly say they feel that their spiritual and secular aspects are completely integrated.  “The Women I have spoken with in many countries have spoken to me about compartments and that their spiritual self is in one drawer protected from their sexual self which lives in its own detached realm. There has to be a way where we as women can integrate our spiritual self and our passionate self that is harmonious.

Amos also wrote from the perspective of a mother. The beguiling Rose Dover – mid-Seventies Queen meets Joni Mitchell – is a musically adventurous yet emotionally reassuring lullaby handed down to her 13-year-old daughter.

“Tash is a huge influence on the record. She also sings on a song called Promise. When she was younger, the conversations of course were different. The exposure in the last few years to what she’s reading, listening to, watching, and how she sees the world – she has become a muse for me. Because I look through her eyes and am exposed to things that I wouldn’t be exposed to if I were left to my own choices. So watching what inspires the conversations that 13, 14-year-olds are having is really interesting. And how to grow up with your imagination intact, how to not have that destroyed, is very much Rose Dover’s story.”

Then there’s Trouble’s Lament, an eerie Southern blues song in which Amos’s matchless voice conjures up images of how the “flames from Satan’s tongue are charged and licking at her heels…”

“Having been born in North Carolina, the South walks with me wherever I am in the world,” she nods. “I can’t get it out of my DNA. I don’t know if it’s a genetic thing, ’cause my mother’s side, so far back, is from the Eastern Cherokee nation. So it’s really in the blood. It’s almost like you listen to the land speaking to you. And wherever I am I can hear the South calling me.”

America’s South also makes a tangential appearance in Giant’s Rolling Pin. It’s a pithy, spry, jig-like satire on the NSA/Edward Snowden affair that also references the magical, truth-giving powers of pies made by “Beth”, “Marlene” and “Caroline”, three remarkable women based out of a café near Amos’s beach home in Florida.

“I love these women! You look out of your glasses at them and think they’ve got some kind of alchemy going on in that kitchen. You just feel better when you’ve had their food!”

As to how the revelations of the NSA’s mass spying on the civilian populace impacted on Amos, she replies that she responded the only way she knew how.

“As an American you have to ask all kinds of questions, and as a writer you have to, too. You have to think, yeah, probably everybody does spy and not just the security arm of our governments. But, um, interesting choice to run and hide with the Russians, who are really great to gays and women!” she notes archly of Snowden’s choice of asylum. “I’m not,” she adds, “being one of those crazy American patriots. But as a writer I try and pull back and be fair. And you kind of think: wow, these revelations needed to happen, but some of ’em didn’t. When you’re putting certain people’s lives at risks you have to ask yourself would I have gone that far.

“So it’s a commentary on all those things. It’s about the taxman as well – there are no checks and balances with our tax authorities. I try not to pick a side when I write like that.”

From global and institutional politics to personal and emotional ones: Oysters is a classic Amos piano ballad, evocative of her timeless breakthrough album, 1992’s Little Earthquakes.

“There are references to surviving, and how things from your past stay with you. Experiences stay with you. And you have to find a way to create with them. Or the voices in your head can intimidate you. Can make you doubt yourself. Self-doubt can be a harmful bully.”

This theme, she adds, is explored elsewhere on an album written over the past few years and entirely recorded in her Cornwall studio with long-time collaborators Mark Hawley and Marcel Van Limbeek, “working as a triangle”.

The return, as it were, of guitars isn’t even the half of it. Tori Amos has been away – diving off the edge, shining a light on the past, peering under the curtain, interacting with musicians and choreographers and writers and women aplenty – but now she’s back. She’s changed, and she’s happier – buzzier, busier – for it. Coming next: an 80-date world tour, just her and her piano.

“Working with all these people made me see and hear things in a different way. Watching other creative people and how they approach things – it really has been life-changing for me,” she beams.

“I wouldn’t have known in 2009 that by 2014 I would really almost have a fresh approach to creating and working. And having worked on a musical with all those people really got me to think about structures. And on this record I brought a lot of what I explored writing for different voices and instruments.”

But don’t take her word for it. Unrepentant Geraldines’ creative consultant has a view, too.

“Tash said something to me. She said: ‘you know, your albums, I’ve always seen them as being a certain phase you’re going through…’ This is my 13-year-old telling me this! And she said: ‘I don’t see this as a phase. I see moments of all your records. And then things that I’ve never heard before, that might have come from the musical. You’re starting to write certain stories from the perspective of being a mom, and from being 50. Because you’ve lived.’”

For all her lyrical acuity and mum-smarts, Tori Amos couldn’t have put it better herself.