"I'm a Christian, so I wanted to do something about it - but of course you don't just hare off and do something like that."
Three things kept her in Wanganui: her dog, house and job.
"Once my dog died, things started falling into place."
Her son told her about friends whose organisation was looking for a nurse to work with rescued sex workers. Ms Southcombe had every requirement needed, including specialising in sexual health.
So she quit her job, found tenants for her house and headed for Cambodia.
For the past year, Ms Southcombe was based in the Cambodian capital, Phnom Penh, where she volunteers her nursing skills towards looking after 45 former victims of trafficking.
She works for an Australian non-Government organisation called Bloom. It rehabilitates rescued prostitutes, educates them - most can't read or write - and teaches employment skills.
She looks after their physical well-being, with many having stomach and teeth problems. She also teaches them how to care for themselves. Some are drug-addicted.
The girls, aged between 17 and 22, are trained to work in the Bloom Cafe in Phnom Penh and to make beautifully elaborate cakes. So spectacular are the cakes that they have received commissions from the Cambodian royal family.
"They are such beautiful girls, and you just can't believe how creative and clever they are," Ms Southcombe said.
"They have been through utter misery, but they develop mana through their work with Bloom."
Bloom has 15 Cambodians on its staff, plus foreign volunteers. Ms Southcombe said although it was not there to make a profit, the cafe and cake business turned over enough money to pay the girls for their work.
She said the sex trade in Cambodia was big business, but it caused endless misery and suffering for those trapped in it.
"There is so much poverty in Cambodia that these families have no choice but to sell one of their children, so the rest can eat. It is heart-breaking."
A conservative estimate puts the number of trafficked children in Cambodia at 100,000 per year, some of them as young as 4. They can be raped up to 40 times a night. Ms Southcombe tells the story of one of her girls who was forced to live on the streets at the age of 5 to escape a home of abuse.
A pimp picked up the child and she was taken to Thailand to work as a prostitute.
Now rescued from the sex trade and rehabilitated by Bloom, the girl is about 21 [she doesn't know for certain] and has no family support.
"But she is an amazing cake maker. And she's streetwise - she doesn't suffer fools."
She describes her year in Phnom Penh as rewarding and humbling.
"It has been the most amazing journey of my life. I wouldn't want to be anywhere else - I'm helping change these girls' lives."
Ms Southcombe will return to Cambodia in mid-January.
While in Wanganui, Ms Southcombe will run a public screening of a documentary about sex trafficking. It will be held at 7pm on January 11, at St Joseph's Hall, St Mary's Church, Guyton St. Entry by koha donation. All welcome.
