1. What was the happiest time of your life?
Now. Being with my husband and also the years I had on my own, before him. I was single for about eight years and I learned to be comfortable with myself and not need somebody. I just wanted to concentrate on my work and on me during those years. I'm a real recluse anyway. I'd bought my little house and I took pleasure in gardening and decorating, taking walks in the forest and just mucking about.
2. Your husband is TV producer Steve Butler. How did you meet?
He worked for 60 Minutes and they did a story on me. I remember I thought "what a neat guy", but I thought he was about 10 years younger than me. He's a very fit man, a surfer. I didn't want someone younger - I'd done that before. Then he started ringing me. We spent a year on the phone talking for hours at a time, never even meeting. It turned out the age gap was only about four years. So anyway, we're married now. Steve and I are different politically. He votes Labour and I vote National. I'm a businesswoman and, let's face it, he's in television and they're all liberal. But we learn a lot from each other, I guess I learn to be a little bit more tolerant and he learns to perhaps not be so naive about people.
3. How many times have you been married?
This is my fourth. The first time I had no choice, I was 15 and pregnant. Back in those days no one talked about birth control so after I had my daughter, bang I'm pregnant again with twins. I was 16 with three daughters under a year old. That marriage lasted two years before I caught my husband in bed with my best girlfriend - a double whammy of betrayal. I was on my own from 18. I could see that boys my age couldn't cope with me and three kids and I thought, if I'm going to have an old guy I should have a rich one, so I got a job at the National Party for God's sake. And that's how I met my second husband who was Croatian, 18 years older than me, very wealthy and kind of arrogant. Funnily enough, we're good friends now.
4. What about the third marriage?
Rebound. Shouldn't have done it. Madness, madness. I'd just come out of an abusive 14-year marriage and should have stayed away from men, but I was damaged. But I don't ever look at my marriages as failures; the first three, to be honest, were all around the survival of myself and my girls. This fourth was the love marriage, the first time I wore a proper wedding dress. It was cream.
5. Do you have advice for teen mothers?
It's got huge benefits if you have good support as I did from my parents. This month I'm going to be a great-grandmother and I'm only 61. I got a call from one of my daughter's friends the other day and she said, "oh Julia I've been watching you on TV and I remembered how I used to think what a cool mother you were because you had a full-length picture of Rod Stewart in your lounge". But what she didn't realise was that I was a kid, my house was just like my bedroom, I still had posters!
6. Is it a contradiction to be a private investigator with a public persona?
Yes but I've always had a good business side to me and I realised that if I got someone else to do my work for me then I could be the face of what I do. I mean people still get scared when they see me, they move out of the aisle in the grocery store when I come down because they think "my god here's that woman, who is she following?" But it's not me doing the investigating, hasn't been for years.
7. What would cheaters be surprised to learn about your methods?
On a computer everything that's been deleted is not actually deleted and if that computer is matrimonial property then a wife or husband can bring it in and it's legal for us to drag everything out. If a car is matrimonial property we can GPS a vehicle and find a partner going somewhere completely different to where they said they were going.
8. How many marriages last after these discoveries?
It's different for different socio-economic groups. A lot of my clients are high end, so they look at social standing, the stigma of being on your own, the kids' private schools, the holidays and they stay for those reasons. But they aren't happy, you don't ever get past it, you'll always be a watchdog. It's the people who haven't had as much privilege who actually say, like I did when I was a kid, "sorry, no way am I going to tolerate that".
9. What were you like at school?
I was a disaster. I went to an all-girls school run by an old spinster. I'm dyslexic and back then they just thought I couldn't learn, so they felt it better if I leave. Was I kicked out? I think I probably was but it was all done very sedately. My parents were called up to the school [and told] I was just too unruly and I left. I was 14.
10. Did you have siblings?
I have a brother a couple of years older than me but we're estranged and have been for many years. He can't really cope with me. I think it was the whole thing of my having had the kids young and the different way our lives went. We've had no contact since my mother died, 31 years ago now. We're just very different. It happens in families, it happens. It's not something I miss or anything. I've got a lot.
11. How do you maintain your immaculate appearance?
I bike and I do exercises to keep the bod. I've never let my face get sunburned. I don't smoke and didn't start enjoying a wine until I was well into my 40s. I think Botox is fantastic. It was Charlotte Dawson who hounded me to have Botox. She always said, "it's prevention, it will stop the wrinkles from coming" and it sure has. You see my photo - okay, it's a tad airbrushed but I'm pretty much the same as I was 15 years ago.
12. Is it easy to get a jaded view of human nature in your line of work?
No. It makes me grateful for the way I am and what I have. I'm a happy, nutty person. I'm a joker. People see these cold blue eyes and this woman who's meant to be tough but if they could see me in my garden with a ton of cat food feeding these stupid pet birds I've got ... I'm a contradiction in terms of how I look and who I really am. My kids know I'm mental, I'm nuts.