There's plenty of British-created curries or ones that have been heavily modified in the UK. If you went to India and wanted a tikka masala. I imagine it would be pretty hard to find one, and if you did it wouldn't be like it was in the UK.

Personally I do prefer Indian curries because they get more interesting with the veggie ones though.

According to that logic, Pizza Hawaii is an Italian specialty

Stole it? I think adopted is more apt. And curry isn't one thing and varies from region to region in India. But Britain loved it so much that there is an Indian (or Pakistani) restaurant practically everywhere. And while Indian / Pakistani chefs have invented new dishes (e.g. chicken chasni is the best goddamned curry ever), I wouldn't call it cultural appropriation.

That's the Indian national dish

Uh, no it isn't...