There are no songs, no glitzy dance routines and all the dialogue is in English, but Bollywood's latest offering, about a dysfunctional Parsi family, has defied convention by becoming a box-office hit.

The world's largest film industry by output and ticket sales draws its strength from the country's Hindi-speaking heartland, but these days it is also reaching out to the country's growing middle classes in its fast-modernising towns.

Filmmakers are already experimenting with bold themes like sex and relationships. Some have even ditched the megawatt song and dance routines which have been the staple of Indian cinema.

Being Cyrus, starring one of India's hottest stars, Saif Ali Khan, takes an even bolder step -- by filming in English.

"So far, English films in Bollywood were marginal films, but Being Cyrus is going to change that," said trade analyst Taran Adarsh.

"It marks the arrival of English films in Bollywood and we will now see more and more of them."

"Being Cyrus" tells the story of a young conman (Khan) who takes up lodgings as a paying guest with a quaint dysfunctional Parsi family and then turns the relatives against each other.

The slick, low-budget production opened two weeks ago and has so far grossed nearly $700,000 -- a small number for a traditional Bollywood hit, but an encouraging figure for an English-language film in India.

"This is the first time that a big star (Khan) has starred in a Bollywood English film, bringing a stamp of approval for this genre," said film critic Vinod Mirani.

Industry officials ascribe the success of Being Cyrus to two reasons -- first, a growing English-language audience and second the growth of multiplexes.

India has around 350 million people who are comfortable conversing in English, roughly equal to the combined populations of Britain and the United States.

Many of these people go to watch films in swanky multiplexes, one of the most visible symbols of India's economic growth.

"The small multiplexes have created a market for different kinds of cinema and the new generation filmmakers are aiming to cash in on the educated, well-groomed audience who go there to watch films," said Adarsh.

"It is a learning experience for many (filmmaking) people that the Indian audience has moved on," top Bollywood director Karan Johar was quoted as saying by a daily.

Bollywood's first mainstream English-language film was English August -- about a young bureaucrat's life in a small town -- released in the mid-1990s.

Hailed by critics, the film bombed at the box office and it wasn't until 2002 that another English-language film -- Hyderabad Blues -- was made. It fared a little better than the previous one.