How many of you have forgotten to lock your front door at night only to come downstairs in the morning and be shocked to find that nothing has been stolen? Hardly surprising, really. Regardless of which crime statistics you choose to believe, the actual chance of an average household being burgled is about once every 35-50 years.

A recent report on crime trends points out that 50 per cent of burglaries are "thefts of goods of small value by children from the homes of near-neighbours or even friends and relatives." Ever has it been thus. Unfortunately, the fear of crime is often inflamed by the very security consciousness that seeks to address it; and so still we try to devise more and more ingenious ways to keep over-hyped intruders out of our houses.

Actually, domestic front door locks haven't really changed for a hundred and fifty years. The materials are better and their appearance is more varied, but their essential operation is unchanged. Yale even promotes itself as emulating the traditions of Egyptian locks and keys – dating back to Nineveh and its palaces, four thousand years ago.

These ancient locks used a hollowed-out bolt, which was held in the locked position by wooden pins that dropped into holes in the bolt. The only way to get the pins out of the way and let the bolt slide open was to insert a wooden key into the hollow of the bolt. The upward-facing teeth on the key could then engage with the pins and be lifted to push them up out of the way. The key would then be used as a handle to draw back the bolt.

In the 16th century, Ivan Vasilyevich, Tsar of all Russia, locked his young wife in her room while he went off to war. To make sure no one could use a duplicate key to 'gain entry', he had the locksmith beheaded (those of you on the receiving end of a locksmith's invoice might empathise). Tragically however, unable to get medical help, she died - a trauma that changed him from a relatively benign ruler into the legendary Ivan the Terrible. The locksmith's family probably recognised the signs.

At the turn of the 19th century, British locksmiths Robert Barron and Joseph Brammah developed the idea of having a small key that didn't reach the bolt but acted through intervening moving parts. In these, the lock turns a cam that pulls the bolt back to allow the door to open and a spring usually pushes the bolt back out again. A non-spring-loaded latch called a deadbolt (requiring a key to open and close the bolt) is usually more secure as it is more difficult to push the bolt in from the side of the door.

Jeremiah Chubb of Portsmouth patented the detector lock in 1818, another variation on a theme, which won a government challenge for a lock that could not be opened by any other than its own key. Even a professional locksmith who was imprisoned on a ship in Portsmouth Docks - incentivised with the promise of a pardon and £100 - failed to open it after trying for three months. With this kind of success, Chubb went on to become the benchmark in mass-produced locks for 150 years.

The cylinder pin tumbler lock, by Linus Yale of New York in 1848, uses Barron's double tumbler principle invented seventy years earlier. It has rows of two sets of pins one above the other - the double tumblers - which stop the cylinder from moving. The correct key raises the pins such that the joint between the pins lines up with the cylinder edge allowing it to move and turn the cam.

Ingenious 200 years ago, they are eminently pickable today. But how many young opportunist burglars have the professional integrity to carefully pick a lock to break in? Minimising damage to your satin finish hardwood door is not really high on a burglar's priorities. Insurers will undoubtedly appreciate your kitemarked British Standard 'thief resistant' locks but will reject your claim because of your flimsy doorframes. Housing Associations – advocates of the Litigation Avoidance School of Architecture - often recommend that steel-faced doors be fitted as standard. Painted with a wood-grain effect, of course.

But maybe we should learn to relax a little. If we don't, we can only go down the socially fragmentary route of increased personal security: locks, chains, alarms, sensors and CCTV cameras. After all, American gated communities with vigilante patrols are the most secure, but they are also the most paranoid. Security often leads to more fear than is warranted by the facts.

Don't have nightmares. Although burglary is a nasty crime, once every fifty years isn't bad odds. If you are worried, why don't you leave your door open one night and get it over with - statistically at least. In reality, you'll probably find that no one has bothered to take advantage.