Kolapata - Whitechapel
I was there a while ago. I don't know how it compares to Gram Bangla, as I've never been there, but I can say we enjoyed the Bangladeshi food - particulalry my lamb biriani (Kachi Biriyani, cooked on the bone). They aren't licensed but were quite relaxed about BYOB. The staff were friendly and interested in how we at heard of the place.
The premises used to be the Sita Tandoori, an upmarket restaurant popular in the 1980/90s and my favourite Indian restaurant ever. You can still see some of the original Sita features.