Many Bangladeshis runs Indian restaurants that serve traditional typical North Indian dishes such as butter chicken, aloo gobi etc and not the actual Bangladeshi Muslim dishes. Hence they are call it Indian Restaurant or Indian Cuisine but not Bangladeshi restaurant or Bangladeshi cuisine. They recognised the demand and popularity of North Indian dishes And went for the established market.
Here is an interesting trivia @ Bangladeshis are muslims and consume beef at home but they do not serve it in their North Indian restaurants as the cuisine is Hindu As people including British locals will find something amiss. So you can imagine why UK Indian dishes vary so much in taste to actual Indian food unless the restauranteur is hindu and a North Indian And hence serving his heritage.
As a habit, I always check who the owner's actual heritage before I bring anyone to a new Indian restaurants. Cant go wrong it if its a Patel, Mehta or Gupta.
