Secret affairs are as much a part of modern office life as e-mail and fax machines. But how do you avoid being caught? asks Claire Seeber
One stained dress and a secretary's midnight raid - sordid evidence in what will be remembered as the most famous office affair of all time. Silly, silly Bill! He wielded the power, his sassy young intern swooned - work experience takes on a whole new meaning! Politicians are notorious for doing it with their employees (see Cecil Parkinson, Piers Merchant and Robin Cook, to name but a few.) But Bill Clinton didn't have any old office affair - he had an Oval Office affair. What he didn't bank on was being caught - cigar-handed. The moral of the story is, if you're going to screw at work, don't screw up by getting rumbled.

So how do you have an office affair without being caught? As Monica Lewinsky has learnt to her cost, the number one rule is never to brag to your colleagues (especially during a tape-recorded phone call). Unfortunately, the very nature of the office affair is such that if your thrill is shagging the boss, you want everyone to know - or at least have a damn good guess. Monica was probably proud that she had nabbed the President, but there is no room for a show-off in the office affair.

The Nineties have brought longer hours to the office - the British spend more time at work than any other European nation. Our workmates are almost family. Whereas it is unprofessional to sleep with your secretary, and many companies frown on romance between colleagues, they just can't legislate for feelings. A firm which forbids office affairs is naive, and statistics corroborate this. Over half of us meet our future partners at the office, and more than 56 per cent of married men have had an affair at work - and they're just the ones who are admitting it.

The office affair is as much part of our working culture as the monthly pay-slip. In a long and boring meeting it is difficult to stop the mind wandering. You start to imagine what could be beneath the crisp white shirt. You see your colleague absorbed in doing what they're good at and it makes them more attractive. Then there's the accidental touch over the typewriter, whispered sighs at the water cooler, footsie under the desk. The office affair can be the ultimate temptation.

It is also a risk. Ulterior motives are often prevalent - sex and office hierarchy go hand in hand. Power and ego have oh so much to do with it. Janie tells a cautionary tale. A competent and able manager, she fell head over heels for her boss, Alan. He promoted her, even demoted a colleague so that he could move her to head office. He would wine and dine her on his expense account and bed her in the company flat. She would glow with pleasure as she congratulated herself on being the "chosen one. He could have slept with any woman in our firm". Alan helped Janie buy her house when she was relocated to his home town, without realising that it backed on to his sister's. The couple were spotted in a clinch, his sister rang his wife, his wife rang the personnel manager, who just happened to be a family friend. Janie was summoned into the office that afternoon, advised to get herself a solicitor and dismissed on the spot. Alan never came to see her again and she was paid off - provided she never named the firm. Janie lost lover and career in one fell swoop, whilst Alan moved to bigger and better things. Not surprisingly, Janie felt bitter - but feels it was better that they were caught. "Although the affair and his betrayal were the reasons I lost my job, I'm glad he showed his true colours."

The abuse of power in the workplace is unisex. One successful female executive admits that being frequently closeted in a small office with her deputy meant she couldn't resist him. When everyone had gone home, they did it on the boardroom table. The danger that they might get caught made the sex more exciting - as did the memory of flesh on mahogany at the next morning's board meeting.

The second rule of keeping it quiet is to never do it on the photocopier - particularly at the office party. It is easy to be caught out: e-mail, answerphones, the brilliant but lethal 1471 number and the old chestnut, CCTV cameras. I worked with a man who was happily married and doing famously at work. At the summer party he could no longer contain his passion for a colleague and they consummated their lust against a wall in the company car park. Naturally, the security men were riveted to the screens in their control-room, tapes were circulated (for a price), and by the time the hangovers had set in next day, the affair was office knowledge. (Likewise, mind torrid lift sex - you never know when it'll stick between floors.) Another old boss of mine suspected his wife was doing it with her design partner, but he couldn't quite prove it. It wasn't until she forgot to switch off her mobile while still connected to his voicemail that his worst fears were confirmed. Not only did he hear himself denigrated, but the sweet nothings she whispered to her lover were recorded on her husband's answerphone.

If you're determined to have your cake and eat it, you must beware the bunny-boiler. The Fatal Attraction syndrome is easily set in motion. James got so drunk at his Christmas party that he succumbed to the advances of a colleague. Life at home was rocky, his wife had just had their second baby, and James was working all the hours God sent to support them. His lover, also married, hounded him until he felt forced into leaving home for her. He describes the affair as "a release of pent-up frustration", but soon realised he'd made a terrible mistake. When he tried to leave his lover, she became hysterical and threatening - and he then found out that she was harassing his wife. When the affair did end, they still had to sit less than 10 feet apart in the office, until James could no longer face going to work. In retrospect he describes himself as "a lamb to the slaughter, but at the time I thought I was Jack the Lad". Getting caught cost him his wife and children.

If the sole intention of your office affair is sleeping your way to the top, then it really doesn't do to get caught. A friend of mine confessed that he slept with his much older boss purely for the perks and the hope of promotion. She would send the company car to collect him for their liaisons. How he rued the day when the driver spilt the beans to the office (a prime example of why not to confide in others). Not only did he lose his job when her superiors complained that he was merely her "toyboy", he was the laughing stock of his (now former) colleagues.

If you're still intent on an office affair and you want it kept secret, never show favouritism to the object of your affections. Susie talks of her boss who fell for a colleague. The lover was quickly promoted to a job that she couldn't do, and bad feeling spread through the office. When it fizzled out her boss couldn't demote her and other staff began to leave. He was caught out by his own passion. On the other hand, don't be too nasty to your loved one - it's a tactic that will alert your workmates. Finally, don't get caught by both always being late - and flushed. It's so obvious.

Personally, I've never indulged in an office affair. Work is stressful enough without worrying about a daily meeting with someone you'd happily never see again. I find a bite of the forbidden apple is easily avoided on this consideration. If you do have to do it and you are caught out, just remember, it (nearly) worked for Bill. But also remember, as you sow, so you shall reap...