Hostages are taken for a variety of reasons. The most common one is to get money - referred to as "kidnap for ransom". Terrorist and insurgent groups do it to raise money for their cause; criminal groups do it for personal enrichment. All groups are better placed to take and hold foreign hostages in Third World areas with weak governance.

Some countries and multinational companies are prepared to pay ransoms in the millions of dollars: Austria, Canada, France, Italy, Japan, Spain, and Switzerland and petroleum companies are known to pay. Australia is among the group that does not pay government-funded ransoms on the sensible basis it would encourage targeting of Australians. The "no-payment" group includes the US and the UK.

Sometimes, criminal groups sell-on hostages to politically motivated groups who then use them as political weapons or hold them until a more substantial ransom is paid. In the case of American and British hostages in the Middle East, a common fate was beheading on camera.

If Australians are taken hostage by terrorist or insurgent groups, any ransom money will have to come from their employers or families. If the sole source of money is family members, the amount they can afford to pay will be much lower.

We are not usually in a position to rescue Australian hostages because we don't have the on-the-ground presence (unlike the US, UK and France) to attempt military rescues.

Australian hostages are most commonly contractors, journalists, aid workers, missionaries and adventure tourists.

In Iraq, during the American occupation, as many as 20 Australian contract staff were taken hostage and their release organised by their companies. Most of these cases never got reported to the Australian government.

The best-known Australian case was construction engineer Douglas Wood in 2005. Prime Minister John Howard famously stated that Australia would neither pull Australian troops out nor pay any ransom that might be demanded. Wood looked likely to be beheaded until he was fortuitously rescued by Iraqi forces during a routine security sweep in Ghazaliya.

Non-monetary reasons for taking a hostage may be to seek a concession from a foreign government or apply pressure to gain an outcome the other party wants.

I worked with Terry Waite who was held hostage in Lebanon by the Islamic Jihad Organisation for nearly five years. In Terry's case he was kept "on-ice" as a political bargaining chip.

If money is the sole reason for taking a hostage, governments that don't pay ransoms are likely to be more a hindrance than a help in getting the hostage released. The British government in those cases puts the family in touch with a reputable negotiator to deal directly with the hostage-takers. It then just becomes a matter of how much will be paid.

The commercial negotiator's role is work out how much he can negotiate the price down for the family without sacrificing the hostage's health. Looked at from the hostage-takers' perspective, kidnap for ransom can be risky and onerous because hostages have to be kept healthy and tie up resources. A dead or escaped hostage is of no value.

In 2013, I met with Australian Warren Rodwell who had just been held by the Abu Sayyaf Group in the Philippines. I had met with the group's namesake Professor Abu Sayyaf in Afghanistan in 2012 but that's another story.

In Warren's case, the ASG had initially demanded a ransom of $US2 million, but eventually settled for $A94,000. The family had limited resources and Warren was in failing health, so the ASG took what they could get. Although the Australian and Philippines governments were not prepared to pay for his release, the two governments made sure the family's payment reached the ASG and was not fraudulently misappropriated - as had happened in a previous Australian case.

There is of course always a role for "quiet diplomacy", but it's mainly to do with working with foreign governments and liaising with family members. The problem with quiet diplomacy is that there's no accountability and no one except DFAT knows what's been done - or not done. For example, questions should be asked about why Australian Dr Ken Elliott - who has been held hostage in Mali since 2016 - wasn't included in the swap of one French and two Italian hostages in return for 200 jihadists that was negotiated by France and Mali earlier this month.