There are not many sports that can keep an audience enraptured through 45 minutes of ceremony before the first point is even contested. And yet, the intricate traditions unfolding in a small clay ring - virtually unchanged in hundreds of years - managed to do just that.

Welcome, then, to the Grand Sumo Tournament - a five-day event at the Royal Albert Hall featuring 40 of the very best sumo wrestlers showcasing a sport which can date its first mention back to 23BC.

London's Victorian concert venue has been utterly transformed, complete with a six-tonne Japanese temple roof suspended above the ring. It is here the wrestlers, known as rikishi, will perform their leg stomps to drive away evil spirits, and where they will clap to get the attention of the gods.

And above all this ancient ceremony, a giant, revolving LED screen which wouldn't look out of place at an American basketball game, offering the audience all the stats and replays they could want.

Sumo may be ancient, and may have strict rules governing every aspect of a rikishi's conduct, but it still exists in a modern world. And that modern world is helping spread sumo far beyond Japan's borders.

It was a random video that first caught Sian Spencer's attention a couple of years ago. This was quickly followed by the discovery of dedicated YouTube channels for a couple of the sumo stables, where rikishi live and train, waking up early to practice, followed by a high protein stew called a chankonabe, and then an afternoon nap - all in the service of bulking up.

Then she discovered the bi-monthly, 15-day championships, known as basho, and from there, she was hooked. The London tournament was simply a once-in-a-lifetime, not-to-be-missed opportunity to see it all in real life, the 35-year-old says.

Julia and her partner Cezar, residents of Edinburgh, discovered sumo through a trip to Japan six years ago. We saw it as a very touristy activity, but we actually ended up loving the sport, says Julia.

Going to Japan is almost the only way to see a top-flight sumo tournament. This week's event in London is only the second time the tournament has visited the city - the first time was in 1991.

For many, the London tournament is the first time they have watched sumo in person - and it doesn't disappoint. Seeing it up close, you get a sense of the speed and the power which you don't get on TV. It was incredible, says Caspar Eliot, a 36-year-old fan from London.

Caspar and his wife Megha Okhai had been among those lucky enough to get tickets when they visited Japan last year, only for them not to arrive in the post in time. It didn't stop them falling head over heels, however, and they have watched every basho this year.

Caspar proudly displayed his sumo towels, representing his favorite rikishi, and commented, I think we had four devices trying to book tickets. The excitement is palpable as audiences embrace both the rich history and the modern adaptation of a sport that continues to evolve within its cultural framework.