The promo was unveiled with the UK print of Dharma Productions' remake project Agneepath.
Distributor Joe Mirza stated: "Attaching our trailer with a movie that is eagerly awaited is the right thing to do, especially as our movie also lends itself to the action genre, which will help it stand out amongst the other films.
"In three days alone, the first-look video has had over 35,000 hits on YouTube, which suggests that the Bollywood-loving audience is already excited about this forthcoming release."
VJ Asad Shan's debut production is described as a visually stunning film and a breathtaking, stylish and gripping thriller.
The trailer shows how an immigrant living in Britain is compelled to take a life-threatening decision to help his family in India.
7 Welcome to London is scheduled to release on March 9.