"Closing the borders" is not going to change how cosmopolitan London is thank god since over half of the net immigration to this country last year (for example) was from outside the EU.
And half was from inside it. It wont STOP immigration but it will slow it.
That is PROVIDED our politicians stand firm and do not give in to EU bullying to keep open borders
Added to which remaining in the single market, which will IMO be necessary for the UK's economic survival, will mean "accepting" some form of free movement....
I presume crossroads3 that you are not one of the many young British people who cannot afford to buy your own home because of our exploding population.
Why do you actively want mass immigration to continue apace?
Have we not got enough foreign restaurants, fried chicken shops, kebab houses, nightclubs, curry houses, Polish shops, Oriental supermarkets, Black Housing associations, street carnivals, Mosques, Temples, take away vans, shisha bars, Uber taxis, Polish toddler groups to satisfy your demand for "vibrancy"?
How many more immigrants do you want? Ten million? Twenty million? When do you want it to stop?
Waits for the wriggling out of answering to begin... 