Others will explain this better, but here goes.
The most popular type of restaurant/take-away in the UK (I think) is 'Indian' (or Bangladeshi, or similar). The 'typical' or most favourite dish in the UK is Chicken Tikka Masala. Many dishes served in Indian restaurants are unknown in the sub-continent and were created specifically for the British market.
It is a tradition (relatively recent) in the UK, especially after an evening drinking beer, to go for a 'curry', i.e. an Indian-type meal. Macho types go for the hottest, spiciest, dishes, often accompanied by much Tiger or Cobra lager.
I understand that a company somewhere in the UK is now the world's largest producer of Indian food.
HTH.