SHE has arguably had more impact than any other female singer of the past two decades. And Sinead O’Connor has used her time in the limelight memorably. Frank Sinatra wanted to “kick her ass” when she tore up a picture of the Pope live on TV, to protest against child abuse scandals in the Catholic church.

And it’s unlikely that Prince – who wrote her most famous hit, 1990’s Nothing Compares 2 U – will be inviting her onstage when he plays 21 nights in London this summer.

“We wouldn’t be the best of friends – me and Prince,” explains Sinead chain-smoking Marlboros and drinking coffee in her London hotel as she discusses her first album release in five years.

After becoming a mother for the fourth time in December, Sinead, now 40, looks well, although she picks at her arm as she talks and admits she is on Lithium, “among other things”, after being diagnosed Bipolar four years ago – long after Prince attacked her.

“I met him twice when Nothing Compares 2 U was a hit,” she recalls. “At the time he had a lot of female protégées and I had covered his song without having anything to do with him. He invited me to his house in Los Angeles and started to give out to me for swearing in interviews. When I told him to go f*** himself he got very upset and became quite threatening, physically. I ended up having to escape.”

But he’s such a small guy.

“He can pack a punch,” she says. “A few blows were exchanged. All I could do was spit. I spat on him quite a bit.”

Despite her outspoken stance, Sinead admits the pressure of fame caused her to retreat from the music business.

“Every time I came to promote records it was ‘Sinead O’Connor crazy person’, and it was adversely affecting my life,” she admits. “I got tired and depressed. As Fagin would say, I had to review my situation.”

Although only diagnosed Bipolar relatively recently, she feels the symptoms were always there.

“It probably began when I was 23 – I had very loud suicidal thinking that I came close to acting out, but always pulled back because I knew that wasn’t me,” she recalls.

Her astonishing voice is still intact on her excellent new double album Theology, due out at the end of the month. It includes eight original songs, as well as covers such as the new single – a version of Andrew Lloyd Webber and Tim Rice’s I Don’t Know How To Love Him from Jesus Christ Superstar.

Inspired by the Old Testament Books Of The Prophets, the album deals with timeless themes of suffering, religion and war.

“This record is something I’ve always wanted to do, since I was a kid,” Sinead explains. “The Old Testament is dramatic, colourful and very emotional. The album is dedicated to this old priest at the college in Dublin. He would read the scripture with tears in his eyes, he really brought the words alive. It wasn’t at all like Mass.”

The record reasserts Sinead’s primary goal of making beautifully original and provocative music. On her forthcoming world tour, old favourites will be played, and although she doesn’t want to dwell on her past exploits, she admits a fondness for them.

“There’s a sense of mischief there that makes me smile,” she admits. “But you don’t always want to identify with your past. It became so bad that at one point I thought if I did jump in the river to rescue a kid someone would find a way to report it to make me look a c***.”

Indeed, when she reported her Pogues pal Shane MacGowan to the police in order to stop his heroin abuse, she was called a snitch by one music paper.

“I adore the guy and I did it because I didn’t want him to croak,” she says. “I’ve seen him lots since and he’s said that if it hadn’t happened he would be dead by now.”

Sinead’s survivor’s story – teenage delinquency and reform school, abuse by her mother, fame and outrage before returning home to be a Dublin housewife – would make an incredible book or a movie.

The story of how she ended up having four children by four different fathers is a tale in itself. For instance, she got pregnant with her first child after going out with her partner for only a month.

“A girl I knew said the 14th day was the only safe day to have sex,” she explains. “In fact, it was the only unsafe day.”

Her second came when a pal said he wanted a child but not a long-term commitment. “I was crazy enough to say, let’s have a baby,” she laughs.

“The third one I actually had my period and didn’t think I could get pregnant. But my fourth (now six-month-old) baby and I are still with the father – that’s a very solid relationship. We’ve been together a year and a half.

“Well,” she adds with a laugh, “that’s a long time for me.”

(c) 2007 mirror.co.uk