In an interview with the Campaign for a Woman Secretary General, Clark was asked how important it was for the Secretary General to be an inspirational figure.

She replied that it helped in a troubled world.

"I look, for example, around the world at who is providing a sense of inspiration and hope at the moment. It's the Pope. I am not a Catholic but I recognise in this man tremendous goodness. A voice of sanity in a troubled world, often speaking what we all feel but could not express as eloquently. So, yes, leadership matters."

Clark describes herself as agnostic and although she does not agree with some of the positions the Catholic Church holds on issues such as abortion and homosexuality, in her role as head of UN Development Programme she has met with and praised Pope Francis for his stance on issues such as climate change, poverty and refugees.

Both Pope Francis and Helen Clark are also fans of social media such as Twitter.

Clark does many of her own tweets and instagram posts: "I think leaders have to be personally engaged themselves, the public kind of know if it's not your own words and thoughts."

In the interview, she said the toughest choice she made as Prime Minister was in responding to the September 11, 2001 attacks in New York.

She said the decision to send the SAS to Afghanistan was "a tough decision" - but did not make any reference to her decision to turn down a US request for countries to join in the invasion of Iraq.--NZ Herald