"...The historians of ethnic food Peter and Colleen Grove discuss various origin-claims of chicken tikka masala, concluding that the dish "was most certainly invented in Britain, probably by a Bangladeshi chef".[14] They suggest that "the shape of things to come may have been a recipe for Shahi Chicken Masala in Mrs Balbir Singh’s Indian Cookery published in 1961".[14]..."
From earlier in the same section: "The origin of the dish is disputed. One explanation is that it originated in an Indian restaurant in the United Kingdom,[3][7] but probably from the British Bangladeshi community which ran most Indian restaurants in Britain.[7] Rahul Verma, a Delhi expert on street food, offered a different explanation, speculating in 2009 that the dish may have originated—probably by accident with subsequent improvisations—in the Punjab and Uttar Pradesh during the last 50 years.[1]"
"...The historians of ethnic food Peter and Colleen Grove discuss various origin-claims of chicken tikka masala, concluding that the dish "was most certainly invented in Britain, probably by a Bangladeshi chef".[14] They suggest that "the shape of things to come may have been a recipe for Shahi Chicken Masala in Mrs Balbir Singh’s Indian Cookery published in 1961".[14]..."