THINK PRIVATE DETECTIVE and what springs to mind? The worldweary, chain-smoking Philip Marlowe? Sherlock Holmes solving another crime with his sidekick Watson? Even Magnum P.I. and his impressive moustache jaunting around Hawaii in a flashy sports car? And really, who could blame you?

Over the last century, few professions have been infused with as much daring, glamour and intrigue as that of the private detective. As a trip to the crime section of any book shop will reveal, authors have always been fascinated with private investigators, while Hollywood and television annually churn out yet more films and shows on detectives, the vast majority of which only add further mystique to the sleuth. Still, one thing holds true: as you might expect, private detectives are a suspicious bunch and none of those I spoke to would allow me to use their full names or have their photographs taken.

"Sad to report, but for the most part, the reality of being a private detective is not like it has been depicted in television, films or books," says Ron, a private detective with Dublin firm Eye Spy. "No two days are the same but it's not international espionage or fortunes-at-stake stuff. I've yet to see a private investigator driving a Ferrari, although there are a couple who wear sunglasses day and night -- but that wouldn't be my idea of blending in."

So that rules out the fedora and the pipe, then. More bad news for those seduced by movie depictions: the work of a modern-day private investigator is not about halting criminal masterminds (intent on world domination, naturally) or dodging the amorous advances of femme fatales. Instead, according to Ron, it fits into three general categories: domestic, industrial and insurance.

"Domestic essentially covers spouses or partners wanting to know something about the person that they are living with. That's usually whether they are having an affair or doing something they shouldn't be.

"Commercial is anything to do with business when there is a problem. That could be internal or external theft, employees claiming sick benefits when there is nothing wrong with them or double jobbing.

"Finally, insurance detection is when a claim has been made and I investigate whether it is genuine or the claimant is just looking for an unwarranted pay-out."

Another detective, Shane from 1st Priority Investigations, says the diversity of the work is what keeps things interesting. "There's no such thing as a typical day. Depending on clients and cases, you could be serving papers for a solicitor in the morning and doing some surveillance work in the afternoon or evening. I've worked in the business for 11 years and no two days have ever been the same."

Blending in and gaining information without drawing attention to yourself -- except in rare circumstances -- is one of the main attributes of the job. It's only here that fact and a little of the detective fiction actually converge.

"Sometimes you might need a disguise to get some information," says Ron. "Dress a certain way and people will think you're a postman, repair man or a motorbike courier without you having to say anything. People make assumptions. In the past, I've dressed like a priest and people just assumed that I was one. But we don't go around peeling off a mask like Tom Cruise in Mission: Impossible."

Perhaps the biggest money-spinner in modern-day private detection is providing evidence of extra-marital affairs. One firm, Cheaters.ie, deals exclusively in infidelity cases. The man I spoke to from the agency didn't want his name used for fear of reprisals from aggrieved subjects of former investigations. Sound a little too cloak and dagger?

"We've received death threats from people we've proved have been having affairs," he says. Perhaps not, then.

"When their indiscretions have been revealed to their partner, they look for someone to blame -- that usually ends up being us. But if they weren't doing something wrong in the first place, there would be no reason to call us."

The odd lunatic threatening GBH hasn't discouraged business, which is booming. Suspicious minds are all too active in many relationships and the days of 'what goes on tour, stays on tour' are long gone.

"A typical client is someone who is concerned that their husband is cheating. It's not uncommon for us to be asked to shadow a stag party by a concerned partner to see if there's anything untoward going on. Whether it's Prague or Budapest -- we've spent entire weekends following stag parties and reporting back our findings. You might find that surprising, but there's no shortage of lengths that people will go to find out whether their partner is having an affair."

He recalls the case of a woman who contacted the agency to learn whether her husband was having an affair. Employed by the woman, Cheaters began its investigations and started supplying regular updates via text message. The husband's suspicions were aroused by the number of texts his wife was receiving from a number he didn't recognise. He then contacted Cheaters saying he was worried that his wife was having an affair.

"He checked her sent messages folder and saw that there were texts like: 'He's gone out now. Call me'. He didn't realise that the messages were actually from us about him."

And there's plenty more tales like that. However, he draws the line at so-called honey traps -- where an unsuspecting partner is propositioned by an employee of a detective agency -- to learn whether they would have an affair. Or, at least, engage in a bit of slap and tickle behind their partner's back.

"We thought about providing that service but a solicitor told us it could be seen as entrapment."

The practice of honey traps is not widespread in Ireland, says Ron from Eye Spy.

"We wouldn't do honey traps. We investigate situations, we don't create them and that's what a honey trap essentially is -- manufacturing a scenario where one didn't exist previously. Honey traps are big business in the US and the UK but I would like to think that most Irish private investigators have a little more morality."

It's not the only thing he won't do. In the business for the last 18 years, Ron says that he's had some very strange requests since he started out as a freelance contractor specialising in motorcycle surveillance.

"I've been asked to beat people up. Other times people will request something underhand. We obviously don't do anything like that. We are not thugs -- we provide a service of gaining information about a subject. The one thing that you don't need in this business is a criminal record. No private investigator I know will break the law because you could lose everything -- your career, your business, everything. We have a code of ethics and we follow them rigidly."

Technology has also made the business easier. Gone are the days when a private detective had to spend hours shadowing a subject in order to find out what they were up to. The advent of satellite tracking systems means that the modern-day investigator doesn't even have to leave the office.

"The private investigator of today is completely different to what it was like when I started. Back then, if I wanted to know what someone was up to, I'd have to physically follow them all day or night. Now I can sit at home, open a laptop and track the whereabouts of their vehicle, 24/7."

So be warned. Next time you head off on that boys/girls-only weekend, remember that someone could be watching you. And chances are, they won't be sporting a fedora or driving a Ferrari. HQ

1st Priority Investigations, Tel: 01 679 3290; Eye Spy, Tel: 01 822 6629; Cheaters.ie, Tel: 01 458 7325

- Garreth Murphy