BIG BARRIER: The giant lock and key on display at Trusty's store in Kolkata

Here's a key you will not lose in a hurry. It is a solid piece of brass and gun metal, weighs about 5 kg and has teeth the size of a standard calculator. And it is more than a foot long. You have seen enough of these monstrosities being presented to celebrity citizens by mayors. So what's new? Look carefully and you will notice this is not one of those ceremonial "Gates of the City" dummy keys. This one opens a real, gigantic lock. And behind them the Lord of Puri remains safe and secure.

A few weeks ago, both the giant lock and key, crafted by Kolkata locksmith Jitendra Prasad Singh, were handed over to the management of Chhotiamuth Jagannath temple in Puri. It all began when the authorities faced the mind-boggling task of securing the new 1.5-ton temple gate, and no ordinary lock would do. They approached Trusty, Singh's company in Kolkata, to help them out. It came up with the giant key and the 2-ft tall, 1-ft wide lock that weighed 80 kg.

When the temple authorities commissioned Singh to make what is probably the world's largest lock, he did not have to think twice. He had travelled down the path before. A similar assignment, 41 years ago, had put him on the path to the manufacturing of gigantic locks and keys for special occasions. In 1961, Queen Elizabeth II was visiting India, and prime minister Jawaharlal Nehru wanted something truly impressive to wow her. He summoned Singh's family from Kolkata with a request: they were to make the world's largest lock for the World Trade Fair to be held in Delhi that year. "At that time, it was a tricky proposition," says Singh, whose family-run business of handmade locks was set up in Kolkata by his great-grandfather Batuk Singh. "But I was determined to make an impression on Pandit Nehru."

Three months later, Singh arrived in Delhi with his creation-a huge lock that was 2 ft high and weighed over 50 kg. It is not clear if the Queen was impressed, but Nehru certainly was. A few weeks later, he called Singh with another challenge: make the world's smallest lock. Now, the tiny silver item, barely 5 mm high with a delicate key to match, is something of a lucky charm for the Singhs.

A special feature of Singh's mammoth locks is the excellent mechanism within. This was put to test by a three-year-old girl on the Puri lock. She definitely needed some help in holding up the key, but once she had inserted it in the socket, the levers turned quite easily. That is because the grid inside runs on well-oiled ball bearings and a single turn snaps three clasps in place.

If Singh has no competitors in this unique market, it is because he is one of the last involved in the painstaking process of making locks by hand. Machine-made locks are more lucrative and are about five times cheaper. But Singh prefers his somewhat antiquated method: the Chubbs technique of manufacture that the British introduced to Kolkata's locksmiths in the early 1800s. However, Singh has improvised on the method. Instead of producing locks in an assembly line, only three Trusty locks are handcrafted every day and each is unique. The manufacturing unit is now in Aligarh, where it moved lock, stock and barrel a few years ago.

The reason why Singh continues to keeps his patrons happy is because it is not possible to pick or break the locks he crafts. Large locks may be the only solution to check the frequent temple break-ins, and this one from Singh's smithy may be a blessing for Puri, which has seen a spate of idol thefts in recent times. The new lock is so heavy that it requires four men to hold it. Of the three keys made, two are kept aside for daily use while the third remains in the head priest's safekeeping for emergency use. Duplicating the key will take at least five days, says a confident Singh, and will certainly draw attention. And after hoisting an 80-kg lock, he wonders, will a thief have any energy left to sprint away with heavy idols?

The Puri authorities were not the first to be fascinated by the Trusty locks. Singh's workmanship secures many temples in and around Kolkata. The 8 inch lock that holds the gates of the Dakshineswar Temple together is also his creation. Another of a similar size seals the sanctum sanctorum of the nearby Adyapeeth. In Singh's north Kolkata neighbourhood, his handiwork can be seen on the gates of the Baikunthanath Temple.

Singh has installed these locks for free, including the one at Puri, which cost him Rs 35,000. "It is for the best cause in the world," says the obviously God-fearing businessman. "If I donate them to a temple, goodwill and blessings are bound to come back to me." Perhaps that's the key to his success.