Never mind the Romans, what have the migrants ever done for us, as Monty Python might have said but didn't. During the increasingly rancorous and rancid debate about migration, it's a question worth pondering. And there's part of an answer in Birmingham.
The city has its diversity issues, like many on our island, but here's something that might work to national economic advantage. The Birmingham balti curry is in the running for a trademark, making it the first curry in Europe to apply for legally recognised status. Anyone in the world using the unique cooking method would need to refer to it as the Birmingham balti.
It's a big step apparently, placing the balti on a par with Stilton cheese, the Arbroath smokie and the Cornish pasty. And it matters in terms of pounds and pence. "It would be a wonderful boost for this great city's world famous Balti Triangle," said environment minister Liz Truss. "Legally protecting food names creates new jobs and attracts more tourists to the area." Happy days for Birmingham.
But it's not all plain sailing for balti. It's a delicious potential moneyspinner, says the government. It's old hat, claims Madhur Jaffrey, the chef and writer, regarded by many as the world authority on Indian food. "Around the 1980s, I really studied the balti and whether it had any authenticity or not," she told the Cheltenham literature festival. "I think it was just a craze ... I don't think it has origins in any place we would want to visit. I think it will slowly die."
That was a bit of a downer. But Jaffrey is just plain wrong, says my friend Syed Nahas Pasha. He is the man with the job I want: editor-in-chief of the industry magazine Curry Life. "People love all kinds of curry," Pasha tells me.
"People love balti. When I take British chefs to India, they love our curries. I even have hotels in India looking for balti sauces. We have the best spices here. To be honest, after a while in India or Bangladesh, I start missing the taste of our British curries."
So: what have the migrants done for us? A lot more than balti. But in the story of modern Britain, balti has its place.
Balti - soon to be on a par with Stilton cheese and the Cornish pasty? Photograph: Alamy