I live in a city (Brighton and Hove) where the "settled" population is probably in a minority of all those who go to sleep at night within the city boundaries. There are holiday makers, seasonal workers to cater for them, longer term but not permanent economic migrants, language school students, students attending two universities, and many other categories, including vagrants, touring drug dealers and visiting prostitutes.
Every summer the United Kingdom Borders Agency sends a charabanc of officers here and, accompanied by police minders and tame journalists, they raid the restaurants. Usually, they manage to haul in a handful of Brazilians working in kitchens in violation of the terms of their student visas. And that's about it. It's a very expensive day out for the taxpayer who funds the charabanc and it just gives young Brazilians another reason to take home a poor image of the UK.
A cosmopolitan city with a shifting population does have disadvantages. There are too many people with no stake in the city, notably the student population - those who are exempt from Council Tax. They may speak English, their parents may well vote for Cameron, but they still trash the place. After all, at the pinnacle of our society, Mr Cameron's Bullingdon Club proclaims that that is what students are supposed to do.
Some language students are not much better and for local residents their barbecues on the beach become tiresome. But then local residents want the beaches as places their dogs can shit on - so maybe it's quits in terms of anti-social behaviour.
For real trouble, though, you have to look to the youthful part of the settled population living on the big 1930s council estates, often unemployed and unemployable. It's these people who keep the local A and E department busy at weekends
Seasonal employees and economic migrants working long hours in the pubs, clubs and take-aways have to put up with the students and the locals, at all hours of the day and night, and they have my sympathy. I wouldn't like to work in a kebab shop open into the small hours of the morning. People can be very unpleasant, especially those who have integrated into our alcohol-sodden culture.
You do nowadays see young men in Islamic religious garb, more frequently than you see men in dog collars, and you do wonder what they are up to. It's not healthy for young men to get involved with religion. I wish Mr Cameron would say that.