FROM the upmarket surroundings of a Kensington lane you can hear Shirley Manson's vampish cackle float from an open window, writes Richard Purden.

Moments later she greets me with a black shawl draped over her shoulders. The singer's trademark burgundy mane has been swapped for a striking arrangement of electric pink and strawberry blonde. The inimitable dark glamour and star wattage remains, albeit more sophisticated and with a hint of B-movie macabre. 

It's 20 years since Manson emerged as a global poster-girl for alternative rock in the last breath of her twenties fronting Garbage. She remains a compelling heroine: fierce, stylish, acerbic and, in the best rock star way, unapologetically opinionated. Of late her well-established wrath has taken aim at a Wisconsin church promoting pig wrestling, the rapper Kayne West – who she called "the loudest clown in town" – and the click-bait culture of online journalism.

Garbage – Manson plus drummer Butch Vig and multi-instrumentalists Duke Erikson and Steve Marker – are marking the 20th anniversary of their self-titled debut with a special edition release and tour where they are performing the album in its entirety for the first time. Preceding social media, smartphones and the dominance of TV talent shows, the record was darkly futuristic and produced a string of hit singles and sold four million copies worldwide. When it was released in August 1995 it was wildly out of sync with the remnants of grunge and the emergence of Britpop, and even now it manages to sounds eerily fresh with its fusion of atmospheric electronica, menacing trip-hop beats and industrial guitars wrapped up in an infectious pop sensibility. 

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Manson insists Garbage have no truck with nostalgia while suggesting there was a sense of unfinished business in revisiting the debut. "The band are always commenting how rough and flawed it is sonically, even though at the time people were saying the production was flawless. Well, actually it's not. It was an analogue record with a billion and one faults, weird edits and it wasn't necessarily mixed how he wanted it to sound.

"We can still play these songs and not feel excluded from them. For it to be 20 years later and us all to be older, there is something to be said for that. The songs still resonate with us, they are kind of ageless. I think it's a great record of which I am enormously proud. Many of these songs were never performed live so it's like having a new set-list." 

Despite a swift succession of hits including Only Happy When It Rains and Stupid Girl, the band got off to a slow beginning. Vig had cemented his reputation producing albums by Nirvana, Smashing Pumpkins and Sonic Youth that defined the early 1990s. As the news broke of Nirvana frontman Kurt Cobain's suicide, Vig met the potential singer of Garbage for the first time in London. A first audition was arranged in the middle of a bleak US midwestern winter. Manson – who had been in Edinburgh band Goodbye Mr Mackenzie – struggled to cope with the foreign environment while the band struggled with her salty Edinburgh brogue. "Behind the scenes I think people were a little worried that I would not be strong enough to hold my own against this legacy of Butch's."

A start came in the form of lyrics about a ghoulish spurned lover. "They had a couple of ideas, one of them was Vow [which became the debut single]. Butch had a pad with the line: 'I can't use what I can't abuse.' I was like, 'Cool line.' There was nothing finished – they [her bandmates] are not the most lyrically orientated characters."

Manson's devilishly loud laughter echoes around the room before she adds, "They are much more sonic and I'm more lyrical. Words turn me on; noise and sound turns them on. We write in weird ways but particularly back then it was patchwork." In many ways it was the perfect alchemy. Vig wanted to experiment with as many genres, styles and sounds as possible while retaining solid hooks, riffs and infectious pop melodies. Manson had spent 10 years under the guidance of Martin Metcalfe in Goodbye Mr Mackenzie, a fine lyricist and brooding outsider inspired by an art-rock triumvirate of David Bowie, Iggy Pop and Lou Reed with the addition of Nick Cave's pitch-black humour.

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In 2013 the pair performed Sleep with Me, a song written for the short-lived Goodbye Mr Mackenzie side project Angelfish, at an awards ceremony in Glasgow. For the first time in two decades their beguiling stage chemistry was apparent. "It was very special for me to do that and sing again with Martin," says Manson. "For all that I am very verbal and upfront, I would never say there was a time we didn't speak, but there were periods of frost.

"I felt he deserved to be part of that because out of everyone I have ever known in Scotland, particularly in music, we were sort of a team and I wanted to do a song or two with him. I felt it would be a perfect time so I asked him and he very gallantly said yes. We had a great time." 

The Mackenzies remain one of Scotland's great lost acts, deemed difficult and controversial within the industry. Manson played an essential role both visually and in the delivery of her vocals with Metcalfe, so would she play with the group again? "It's hard to think about what it would be like because they don't exist but they could do it without me – I was just backing vocals." Surely a reunion would be inconceivable without her involvement? "Maybe so. What Martin decides for his future I have no idea but what I do know is that he is ridiculously talented."

Manson admits to having always had a "big mouth", especially when she looks back to some often quoted interviews from the mid 1990s. A knack for securing headlines remains intact and she has become something of a cultural commentator on a range of issues using the platform of social media. Earlier this year the singer's opinions became part of the cultural debate dubbed Black Excellence vs White Mediocrity after she posted an open letter to Kayne West which rounded on his criticism of Beck for winning album of the year at the Grammy awards. 

"I mouth off every day," says Manson, "but I never expect people to pay attention. I'm not saying that to be funny or glib. I find it cathartic to write so when the whole Kanye thing broke I was shocked. 

"I think he is an incredible musician who I respect enormously. What disappointed me so much was that someone I admired had drank the Kool-Aid and started to believe, because he has won a few awards himself, that these shows are the true measuring stick of artistry. I was fighting against this ideology that things should be measured and marked out of 10. I mean who believes these awards shows represent what is best in art? You've got to be a bit naive to think it is some kind of true representation of anything."

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Manson also helped bring to an end a bizarre pig wrestling contest in Wisconsin, attracting ire from America's political right for her comments, which included: "Lest we forget that this was in a church, the event involved a pig being smacked around in barrel for sport!"

"I posted on my website thanking fans for getting involved," recalls the singer, "and a journalist took the story and turned it into some weird headline which stated that I loved abortion. They made it sound like I went out and got one every week! Just for the record I have never had one but that's got nothing to do with it. We live in a time where there is a lot of infantilised journalism and ridiculous headlines – the nuances of a story don't get reported."

Transatlantic journeys from her home in California to Edinburgh have become necessity, she says. "According to my husband [Garbage engineer Billy Bush], if I don't get home after three months I start to go a bit weird. I need to be with Scottish people and to feel the cold and rain. It sounds like some pathetic cliche but I have a strong sense of being Scottish and being an island girl. My family history is 100 per cent Scottish with no Irish, Welsh or English. I'm a Viking Scot and I feel like that is part of my DNA – it's impossible for me to eradicate that from my sense of self. It's a huge part of my identity."

Her roots and family lore may span generations in the far north but it's the east coast that stirs and summons something deep within. Her father, a retired lecturer and theologian, would transport his three daughters to the shores of the North Sea where he would amuse them with stories about Scottish literature and the sea. Yellowcraigs in East Lothian was regular destination with its views of the ocean and lighthouse on Fidra, the uninhabited island and inspiration for Robert Louis Stevenson when writing Treasure Island. 

When talking of family and time spent in Scotland, her tone softens. "I would go to East Lothian, where my mother is buried in East Linton. I like to drive along the coast road to see her grave then go along the John Muir Trail to Yellowcraigs. After that I walk to North Berwick hitting the Lobster Shack for some treats and a glass of wine before heading back to Edinburgh. It's an incredible walk, it doesn't matter if it's freezing or beautiful sunshine – it's the most inspiring place. I love the sea. My house in Edinburgh is also by the water, I find it calms all anxiety." 

When in California, a clutch of historical British TV dramas including The Tudors and Wolf Hall provide a diversion. "In America there is so much female tits and arse. Once you have seen everything a billion times it's not very erotic. I've become obsessed with Tudor England and the story of Henry VIII and Anne Boleyn – the clothes are mesmerising. It was such a mad, violent and brutal time. The whole thing has fired up my imagination."

The Garbage tour will culminate in Edinburgh, something of a homecoming show for Manson and the first time she has played in the capital since 2002. Early next year Garbage release their sixth studio album, a record she describes as "more romantic". 

The last album, Not Your Kind of People, released in 2012, saw the band scratch a seven-year itch and was a critical return to form after a time of personal and artistic turmoil. Manson considered giving up music when her record label "took the band prisoner", while alternative rock was pushed into the margins.

"Let's put it in perspective. I'm not out digging roads, saving lives and fighting wars but there is a challenge for every artist to keep going. It's easy when you are in that glorious moment and riding the first wave of success, you just have to hold on for dear life and see where it takes you. But to maintain a career over many years takes of a lot of tenacity and defiance. There is a zeitgeist moment but to keep the engine running you have to rebel against the mores of the day." 

Not long after turning 40 and amid the American obsession with the elixir of eternal youth, Manson contemplated cosmetic surgery. As she approaches 50, Manson appears to have abandoned the notion as she lays into the male gaze agenda of the entertainment business. 

"Women are supposed to always look beautiful and attractive – the minute we no longer do we are relegated to the back benches. When you are 'past your peak' and are no longer the woman that people physically admire, when nobody talks about your beauty or when you are not the prettiest girl in the class, it can be problematic." 

As a teenager she struggled with bullying and body dysmorphia, and during her ascendency in Garbage there were also episodes of crippling self-doubt. "There was this feeling that we were not real or authentic because we didn't look like anyone else. If I saw us now I would be intrigued because it was such a bizarre mix, this cultural clash of American midwestern pragmatics and Scottish swagger but also Scottish self-doubt – those two forces created something unique." 

Manson has gained entry to a small but iconic assembly of female outsiders and misfits every bit as idiosyncratic as herself. "I don't know why but I had great instincts when I was young. I fell in line with Patti Smith, Chrissie Hynde and Siouxsie Sioux – arguably the greatest female rock stars of all time. To this day they continue to light torches for me and all three have conducted themselves with taste, authenticity and credibility. Every time they stand, I stand up with them. 
"When you age as a female in the music industry it gets more and more difficult. There are moments where I have thought, 'I will have to Botox my face or put a leotard on or I'll be forgotten about.' But I'll be damned if someone is going to tell me to stop doing this because they don't consider my age appropriate. I am determined to continue as an artist because I love doing this. I'm sure my appearance is going to change but I'm OK with that."

A 20th-anniversary deluxe edition of Garbage is out now on Stunvolume. The band will play Edinburgh's Usher Hall on November 14. For tickets, visit usherhall.co.uk. Twitter: @garbage