Now executive legal counsel at financial services firm AMP, she says it has been an extraordinarily exciting time.
"Where else do you get the opportunity to sit opposite policymakers, to sometimes sit in a room with senior politicians and give your view around how something would work?
"That would never ever have been afforded to me in Dublin, it just couldn't have happened."
Now when she returns home ex-colleagues are interested in discussing KiwiSaver because it seems so contemporary when compared to European pension schemes, which are yoked to tax incentives governments can no longer afford.
She says the introduction of KiwiSaver has gone exceptionally well, in part because it is a simple, well-governed and centrally administered scheme, although Singleton would like a lift in the minimum contribution rate over time. "I think really a 3 per cent contribution rate is never going to get anybody what they want in retirement."
On a day-to-day basis Singleton describes her role as the conscience of AMP, particularly when chairing due diligence committees.
"I challenge all of my team when we come to draft anything or we come to approach anything with a customer: is this how you would deal with your mother?"
She was also heavily involved in the merger of AXA into AMP, leading the due diligence before moving on to the first phase of integrating the two businesses.
That meant creating a vision for how the new company would operate and winnowing down the offerings - the two KiwiSaver schemes and two sets of insurance products to create a strategy to hand to the integration team.
Singleton's role in the merger of AXA with AMP's existing business saw her awarded Greenwood Roche Chisnall private sector in-house lawyer of the year by the Corporate Lawyers Association of New Zealand.
"I was pleased because from a personal perspective it was really recognition of the journey that I've come on because I literally arrived in New Zealand not knowing a single lawyer in the country and I really did have to start from scratch."
She has now set her sights on helping another young lawyer take their first steps up the career ladder, sponsoring and mentoring someone from a lower socio-economic background.
It stems from her own start in law; seeking to "change the world" at a Dublin firm specialising in representing legal aid cases. "I still have this hankering, this needing to give back to the community like I did from very early on in my career, but I've got two small children and I've got a full-time job and I just simply do not have the time to give back right now."
The AMP-sponsored scholarship is likely to be announced within six months.
She's still got those farewell cards predicting career death.
"I never for one second regret anything I've done around coming to New Zealand. I think it's made my career."
