On a sleepy Saturday afternoon in Slough, a borough west of London, Nidar Singh Nihang knows how to keep a group of young men awake.

Inside an empty hall of a church in London Road, Singh Nihang is an authoritative figure. As 20 men, most of them from the Sikh community, surround him in a semi-circle, he demonstrates some self-defence skills. With subtle hand and body movements, he exhibits a form of martial art that he has mastered over 25 years.

But more than 5,000 years after its inception, this form of Sikh martial art known as Shastar Vidiya could soon be relegated to the pages of a history book. There aren't many practitioners and there is a sole surviving master who embodies the technical and traditional expertise: Singh Nihang.

"My aim as a Gurudev [teacher] is to ensure the art, in all its totality, survives," says Nihang Singh.

In Slough, throughout the three-hour session, the man with an intimidating body structure standing at 6-feet-one-inch, explains about the various techniques and also history behind Shastar Vidiya to casually dressed men, most of them in their traditional turban and beard.

"It's a science of weapons," he says, pausing it to describe it more eloquently, "which involves advancing upon the enemy, hitting in a striking range, misaligning his strikes and cutting them down."

As his students engage in different unarmed fighting techniques, an array of weapons neatly lay on the table. Singh Nihang steps forward, picks up a Maddu, a small weapon akin to a knuckleduster, and tells how it was used during wartime to attack the enemies.

"In the old days, you had to fight people to show your art. Nowadays we can be sensible. We can demonstrate so we can show the art and science behind it," he says.

Singh Nihang himself is draped in a blue Chola, a kurta-like robe, with white Kachera, knee-length breaches, and sneakers. His sword and a traditional dagger are neatly tucked between the blue Kamarkasar (cloth belt) wrapped around his waist.

His traditional get-up and a long beard with streaks of white hair might give an intimidating first impression, but he isn't as fierce as he appears.