Mulligatawny soup, for example, is an Anglicised version of its more pungent Indian forbear which was actually a type of sauce. Similarly, kedgeree was originally a rice and lentil dish but was adapted by the British to be a breakfast dish containing fish. Yet the majority of UK restaurants are run by people of Bangladeshi, not Indian, origin. Their influences are obviously from Bangladesh but the restaurateurs have in turn been influenced by the likes and dislikes of their customers. They have modified dishes and incorporated new dishes from other areas of the sub-continent.
Dishes develop and change according to a host of new influences.
For instance, the most popular curry in UK restaurants is Chicken Tikka Masala. Many people would think of it as a typical Indian dish. But it is actually a restaurant invention created in the UK by Bangladeshi restaurateurs. A true hybrid and a recent chapter in the long history of curry.