The business finally folded last year and Filan was declared bankrupt shortly afterwards with debts reported at £18m and only a few thousand pounds in the bank.
How did your childhood influence your work ethic?
My mum and dad ran a family café in Sligo for 35 years and worked long hours. We grew up in a very hard-working family and had a lovely atmosphere as we lived above the restaurant. It definitely made me want to work hard whatever I chose to do. As the baby of seven kids, I was definitely a bit spoilt. At school I just loved singing and wanted to be an actor or singer.
What was your first job and how much did it pay?
I waited in our café in the summer when I was 14. I got tips for serving teas and coffees and I loved making customers a cappuccino. I got paid £20 pocket money, enough to see me through the weekend and out to the cinema or disco.
What did you blow your first record advance on?
At 18 I bought my first car, a second-hand BMW 3 Series, for £16,000. At that stage we hadn't even released a song. We'd just started recording our album and we all got a few quid. I probably blew half my advance.
Are you surprised at how successful your career with Westlife was?
Every year we couldn't believe it and, even when I look back on it now, to sell 14 million singles, 50 million albums and sell out arenas and stadiums, what Westlife achieved was crazy. It's like One Direction probably don't realise how big they are. They'll look back one day and think, "Holy God, that was pretty amazing."
Did you have an alternative career plan when Westlife split up?
I did but it all went horribly wrong when I started investing in property halfway through Westlife. You get to a stage when things are going great. I started to think: "I've made some money here and I'm 25 years old. I'm still very young. I need to plan ahead."
When I got into property, I'd just had my first baby, Nicole. Brian [McFadden] had left the band a year earlier and we were at a stage thinking it might be over if Westlife split up two years later. I genuinely had no plans but I didn't want to go solo. At the time property was a great thing to invest in and booming beyond belief, like crazy. I invested a lot of money and ended up losing it all. [Shane went bankrupt with debts of £18m.] That was my plan B and it didn't go well, but that's life.
So what advice would you give to boy bands on the brink of fame?
Not to invest in property!
Are you a spender or a saver?
I used to be a spender but now I'm a saver. Money is a very dangerous thing and you've got to know how to look after it. When I had money I felt pressure, whether it was to invest it or do good with it, and I couldn't let it fizzle out. It was like I needed to prove to myself that I could look after it, only I did the opposite, but you have to take a chance in life.
I think if you can be content with just having normal stuff even if you do make money, it's a safer place. Luckily I'm able to sing so I want to stick to that from now on and see what happens.
What's been your most indulgent purchase?
I once bought a four-seater helicopter. I lived in the west of Ireland and I didn't want to drive for three hours so I got a helicopter to make life easier for about a year and a half. I got rid of it even before all the financial stuff happened because it was costing too much. I thought it would be good, pay for itself and I'd rent it out, but it was just hassle.
How did you lift yourself after going bankrupt?
I had a great wife. Gillian's an amazing woman and she kept me very positive. I had three healthy, beautiful, children so Gillian kept reminding me, "Keep looking at them, that's what we have. Don't worry about that, it was horrible but keep focused."
You've got to keep very upbeat. You get scared, embarrassed, and I felt nervous, angry and full of emotion, thinking "Jesus! Why me? How could I lose that, how could I do that?"
But I'm just one of thousands of people who did it. It chews you up inside and you feel so angry that you let it happen to yourself. But then you think, "Isn't it great that the kids are healthy and alive and I'm healthy?" I just started again.
What's your biggest extravagance nowadays?
Simple little things: I love going to the cinema once a week with my wife, where we have a date night with popcorn and ice cream. Or every couple of weeks we go for dinner, share a bottle of wine and talk about everything, just small pleasures, spending precious time together.
Do you prefer to pay by cash, debit card or credit card?
I'm more of a debit card person and I live in the "now". I don't like credit cards any more. I try to live with whatever I can afford and don't try to put myself in an awkward position. I've done that before.
Is there any silver lining after what you've been through?
I definitely look differently at money now. I never want to live ahead of myself any more. Financially I'm starting again from scratch but as long as I can afford something for the next few months that's as far as I look ahead.
Gillian is solid, a rock, a mountain, whatever you want to call her. Gillian's beside me and she's my world. She kept me going through the worst time of my life and loved me then more than she ever loved me. We've been married 10 years this year.
In this business you get to meet beautiful women all over the world but to me it was like, "I'm not messing up what I have." We have something special and, thank God, Gillian is the mother of my three kids.
If your sons wanted to join a boy band in future, what would you say?
I'd say, "Listen to everything that daddy says!" My daughter already wants to be an actress; she's eight and wants to go to drama school. I'd definitely encourage theatre because it's great for kids' confidence, as they have to do job interviews one day and get used to being nervous, so the quicker they do that in life the better. They all sing in tune in the back of the car so we'll see what happens.
What about reality television is that an option?
When we took a year off I got offered a lot of shows, but I didn't want to do it even though some offered a lot of money. It wasn't about money because I had money and it can be catastrophic. To me, it was all about the right decisions for my career and I have to be very careful.
People go on it for lots of different reasons. You do get paid well, it's a job, and lots of people carve careers out of it. Nicky [Byrne] went on Strictly because he wanted to do television and get his name out there so it made perfect sense. Strictly 's a great show so down the line maybe I'd do reality television, but at the moment I just want to sing.
Do you invest in stocks and shares?
Never maybe I should have.
What's your favourite charity?
For me, because I have three young children, kids' charities always touch my heart a little bit more. I'm a patron of Niamh's Next Step for a little girl who suffered from neuroblastoma. Sadly, Niamh died while we were on tour last year.
All that trouble I've been through financially means nothing if one of your kids is sick. It just hit home that despite the whole financial thing, how lucky am I?
After 14 years with the band, is the thought of being a solo artist daunting?
Everything is going to be new for me. The whole interview thing e_SLps I'm taking all the questions, and I've got to be on my game. I've got no time to be hung over or think that Nicky or Mark [Feehily] can answer more questions today. We always protected each other but now I've got to look after me. There's more pressure, without a doubt, but I can't worry. I've spent a lot of time worrying in the past few years but I'm very positive and now I say, "If this doesn't work out, I'll figure out something else."
Shane Filan releases his debut solo single, 'Everything to Me', on August 25 on Capitol Records (shanefilan.com)
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