They are shady gunslingers who operate in secret. They prey on highly unstable countries and have, in extremes, plotted to overthrow entire governments. Mercenaries - or, to use their more modern title, private security firms - have never had a good press.
And new allegations that private security guards abused Iraqi civilians, together with the trial of Sir Mark Thatcher over his alleged involvement in the attempted political coup in Equatorial Guinea, have done little to change the perception of this sometimes lawless industry.
But a group of some of the biggest and most powerful British security firms have had enough. They are tired of the allegations and criticisms and have decided to take action. At a conference to be held at Oxford University a week tomorrow, leading figures in the industry will gather to discuss ways of weeding out the rogue firms in an attempt to create a distinction between the legitimate security companies and the mercenaries.
Participants at the meeting will include the controversial Lieutenant Colonel Tim Spicer, the former Scots Guard who was at the centre of the 1998 arms-to-Africa affair. Lt-Col Spicer is today chairman of Aegis Defence. Also speaking will be Harry Legge-Bourke, a former Welsh Guard and brother of the one-time royal nanny, Tiggy. Mr Legge-Bourke now runs Olive Security, founded three years ago, which has built a big presence in Iraq.
Both men are expected to make a surprising demand. They will argue that the security industry should be tightly regulated and new restrictions placed on their operations.
Andrew Bearpark, the vice-president of special projects at Olive Security, says: "There are a raft of reputable companies. But there is a cowboy end of the market. They are disregarding humanitarian laws and going around killing people."
Mr Bearpark, a former director of reconstruction at the Coalition Provisional Authority in Baghdad, adds: "I am going to propose at the conference that, for example, all security companies train their staff in humanitarian law. And I would like to see all private security companies adopt the laws of the country they are based in, as well as the ones in which they operate."
ArmorGroup, a security firm chaired by Sir Malcolm Rifkind, the former Conservative foreign secretary, will present a "white paper" on the future of the industry. This will call for new regulations to be placed on the firms and will say that the free market has "offered opportunities for ill-prepared or less scrupulous companies to thrive".
The private security industry has boomed in the past three years on the back of global security fears caused by 11 September and the invasions of Afghanistan and Iraq. The Foreign Office alone spent Â£20.2m hiring security companies last year. Of this, Â£14.2m was spent in Iraq. And it is estimated that a tenth of the total budget for Iraq's reconstruction is being spent on security.
London has emerged as one of the main centres of the global security industry, partly because it has an abundance of trained former special forces and intelligence officers, regarded by headhunters as prime security material.
Other reasons for the boom in this British export are the lax regulation and legal loopholes that are being exploited by unscrupulous companies. It costs just a few hundred pounds to set up as a "security consultant" and virtually no proper government checks are made on companies before they are allowed to sell their services to business clients and foreign authorities.
One source at a private security firm says: "Take Iraq. There are a lot of private security personnel who think it is 'Showdown at the OK Corral'. Some of the people out there have 'issues' with past conflicts and they are passing on bad advice to their clients."
The grey areas in the rules pose significant ethical questions, such as when a private security guard or soldier is entitled to open fire. Jonathan Garratt is managing director of Erinys International, a British-based security firm which holds contracts with the US Army Corps of Engineers, the Iraqi oil ministry and private companies. In Iraq, says Mr Garratt, the rules are clear because the authorities have set up guidelines for private security firms. "The rules of engagement are that [guards only open fire] in self defence or to protect lives," he explains.
But in other parts of the world, things are not so black and white he adds. "In countries where there is no government, where there has been regime change, we need international regulation."
The Foreign Office published a Green Paper in 2002 on options for regulating private military companies. The proposals were eventually dropped, much to the anger of many backbench Labour MPs. Now the Foreign Office is taking a second look at the issue and, in the next two weeks, officials are expected to present ministers with a range of proposals, including a new licensing system for companies.
Andrew Mackinlay, a Labour member of the Commons Foreign Affairs Committee which scrutinised the Green Paper, says: "I find it totally unacceptable that these companies operate out of the UK without any regulations." The MP for Thurrock believes one reason for the Government's light touch on security firms is that it relies so heavily on their services abroad. "I am suspicious of the Government using these companies. If things go wrong - some human rights tragedy - then they always have a denial. If a British solder shoots someone then there will be a trial; if a military company screws up then, sure as hell, it'll be out of the country PDQ."
Being an armed guard in a war-torn country is a dangerous but lucrative business. A four-strong ex-SAS unit in Iraq can command Â£2,500 a day and they earn up to 100 times the wages of an Iraqi security guard. But there are concerns that the lure of money could damage the British military as soldiers may be tempted to leave for the private sector.
Andrew Kain served for 17 years in the Army, first with the Parachute Regiment and then with the SAS. In 1991 he set up AKE, a security firm that specialises in advising and training people for work in hostile regions. "If the trend continues," he says, "then the military will simply become a training ground for people who want to join a private military company."
Mr Kain will be in Oxford next week to discuss the future of the industry. Like most of his colleagues, he will call for tighter regulation.
But he has a surprise for the other delegates. Controversially, Mr Kain will argue that many private security companies have no place operating in some of the world's war-torn countries. "I have strong views on the way things are going. I have an issue with heavily armed companies taking over the role traditionally done by the military."
He adds: "If the people who are employing them - be it governments or companies - are planning to foster long-term relations with the communities in which they are based, then they must use local people rather than importing private armies."
Mr Kain isn't expecting to make himself popular by saying this. But if the industry really wants to lose the shady mercenary tag, then engaging with local people rather than importing armed guards may be its best chance.
GUARDIANS OR GUNSLINGERS?
Countries in conflict have become a magnet for private firms trying to cash in on the demand for armed protection and security advice. Most are branded with the "mercenary" tag, but there are really three types of operation.
Private security companies
These work for businesses, governments and non-governmental organisations in dangerous countries such as Iraq and Afghanistan. They can provide anything from staff training to armed patrols and bodyguards. Companies in this sector include Control Risks, Olive Group, Erinys, AKE and ArmorGroup.
Private military companies
These are commercial armies, hired by governments to supplement their own forces. Most are secretive about their operations and this sector is made up of some security firms that conduct military work on the side.
The sector also contains unscrupulous operators that register a business at Companies House for a single mission and then dissolve it. "There are many operating internationally that are little more than glorified mercenary operations," says a report by the Rand Corporation think-tank, commissioned by the Foreign Office.
Two famous examples of private military companies are the now- defunct Sandline International, the company at the centre of the 1998 "arms-to-Africa" affair; and the now-defunct Executive Outcomes, which employed Simon Mann, currently in a Zimbabwean jail for leading a coup attempt in Equatorial Guinea.
This is a pejorative term for private military companies. It is often used to describe the darker - unlawful - side of the industry, involving attempts to overthrow governments. The failed coup plot in Equatorial Guinea is the latest case of mercenary activity. In 1981, Colonel "Mad" Mike Hoare, a former paratrooper, became a household name for his attempt to topple the government of the Seychelles. He and his team entered the island disguised as members of a beer-tasting club called the Ancient Order of Frothblowers, before being arrested.