It's 2 July and a small bearded figure in a white kurta is shinnying up a telegraph pole at Pani Pokhari, unfurling a huge banner across the street. The banner, in English and Nepali, congratulates Jorge W Bush (sic) on the forthcoming US national holiday and is signed Cleaner of Nepal, Laxman Singh Khadka.

No national day or major event would be complete in Kathmandu without one of Laxman Singh Khadka's banners. Whether it is celebrating the friendship between Japan and Nepal, UN-Nepal relations, or congratulating Queen Elizabeth on her 79th birthday, the banners have become a Kathmandu institution.

For the short-sighted, Khadka brings his message down to street level by wearing a kurta which matches his banner. He has two hundred such kurtas and he proudly claims he has never re-used one the following year. The day we met Khadka he was between Popes. The banner commiserating the death of John Paul II had just come down and he was looking for a suitable spot for his banner hailing the appointment of Benedict XVI.

Laxman Khadka has been putting up banners (a total of 100, he estimates) around Nepal for almost 12 years. His first was for Buddha's birthday in Lumbini. His second was for the American national day. "I wanted to do something good for the nation. Everyone is doing things for profit or money. People think I get paid for wearing these kurtas but I don't get a single paisa from anyone."

An energetic 57-year-old, Khadka is a farmer from Tintana VDC. He has four children and used to be a driver in Kathmandu before giving up work to concentrate on politics. His only income is from a small piece of land owned by his family. Every morning he wakes up at six and has tea. Then he goes out, "to scold political leaders, even though they never listen to what I have to say. I'd like to be a minister but I'd be confused about who I would work for: the public or the king."

Khadka writes the text for his banner, gives it to his daughter to translate into English and then takes the text to a sign painter in Baneswor. Each banner costs Rs 5,000. How does he pay for them? "I get credit from the sign painter and friends help me out."

He claims to have always been an independent politician and to be working for the good of the country. "Japan, South Korea and Singapore were all built by their own people. But Nepal can't do it on its own. We need help from outside. Nepal is landlocked, which is a big problem. I'm for democracy and zero corruption. On His Majesty's birthday this year I asked him whether he wanted me to go to India on his behalf as his prime minister. He smiled but didn't say anything."

I ask Khadka whether, in this age of increased security around embassies, he is ever prevented from stringing up his banners. He replies that although hanging banners is illegal, no one has ever told him he can't. "And anyway, everyone from high-level officials down knows me, so they know what I'm upto," he laughs.

Indeed, Khadka is an enthusiastic participant in public events. Last year, following the resignation of Surya Bahadur Thapa, he held court at the palace gates waiting to hear whether his application for the post of prime minister had been successful.

When he isn't putting up banners, Khadka likes to direct traffic. He is often seen at Narayan Gopal Chok at rush hour, cheerfully signalling with his arms and waving to acquaintances. "I like to direct traffic as part of my social work. Traffic police have to stop drivers to look at their licence and ask for bribes."

So what happens to his banners once they have had their day? "My house is too small to keep them all there," he says. "Sometimes we rip them up and use them for cleaning the house. I'm always in search of new occasions for a new banner. I was going to make one after the London bombs but didn't have enough money."