Ali's book, which focuses on an Asian family living in Britain and explores the British immigrant experience, was shortlisted for the 2003 Man Booker Prize.
"It is a big achievement for me because no body has been offered a lead role in Hollywood films except Om Puri. He played the main lead in 'East is East'," Kaushik told over the phone from Mumbai.
"I was not aware of the film till Loveleen Tandan told me about it. Loveleen is the casting director of the film. At that time I was busy with the pre-release promotional work of 'Shaadi Se Pehle' in Delhi.
"She took my pictures and sent it to London. The director and one of the crew members flew down to Delhi. They took my screen test and offered me the role," said the maker of hit films like "Tere Naam" and "Hum Aapke Dil Mein Rehte Hain".
Kaushik, who is also remembered as the lovable Calendar in "Mr India", is flying to London on May 28. He has been on cloud nine since he signed on the dotted lines.
"I am extremely happy with the offer... it is a true international film. I am going to work with the prestigious names like producer Alison Owen ('Moonlight And Valentino', 'Sylvia', 'Proof' and 'Elizabeth') and director Sarah Gavaron."
Kaushik, who always craved for meaty roles that never came his way, says this film will give him ample opportunity to showcase his talent.
"I am a product of National School of Drama and I always thought, why can't I get roles which will allow me to use my theatrical experiences. This film will fulfil my ambition of showing my theatrical experiences."
Talking about the shooting schedule, he said: "For the first two weeks, there will be rehearsals and after that we will start shooting the film."
Kaushik was chosen from among 200 artistes who were screen tested for the role.
However, Kaushik hasn't been so lucky on the home front. His recent release "Shaadi Se Pehle" starring Akshaye Khanna and Ayesha Takia hasn't done well at the box office.
"It was released on the wrong day. Usually films are screened on Friday but 'Shaadi Se Pehle' opened on Thursday. And it is not a flop. I think it is an average film and nobody will lose any money," said Kaushik.