So are the Labour Party. In fact, the British state is excellent at controlling our border, if you mean keeping people out. They are so secure that word has got around and most people don’t even bother trying to get in. Berghain has a reputation for exclusivity, but it is nothing like as selective as the British state.
One of Parliament’s least pleasant anti-immigrant, anti-science libertarians published this earlier:
SW1 gang talk about controlling the weather. They can’t even control our borders
— Douglas Carswell MP (@DouglasCarswell) February 16, 2014
Climate change denial aside, the comment on controlling our borders really rankled. Sure, lots of people have moved to the UK in the last decade, but a lot less than would like to. Douglas Carswell is pretty deluded if he thinks it’s only Poles, Bulgarians and Romanians who want to move to the UK.
Gallup conducted a survey in 2007. Doubtless it’s a little out of date now, but it’s still useful. They asked where people would live if they could live anywhere in the world. They constructed a representative data set and worked out how many people worldwide wanted to move where. The US came top, as you’d expect, and the UK came second. 
150 million people want to move the US and 45 million want to move the UK. That will be a conservative figure as some people would move the UK were it the only option realistically open to them.
So how many people actually make it into the UK? Well, to be fair I’ll use gross migration and include Brits who are just coming home. Net migration is the common figure, but it subtracts those leaving from the gross figures. I want to use the most upwardly biased figure possible. So, for good measure, I’ll take the gross number from Migration Watch: 503,000 by their reckoning.
45 million people want to move here (conservatively) and (as an upper bound) 503,000 actually did last year . That means every year just 1% of those who want to move the UK actually can and do. This figure isn’t meant to convince anyone who doesn’t already agree, but just so you know, anyone who says the British state can’t control its borders is a fucking idiot, Douglas Carswell included.
 If that fills you with dread rather than pride you’re a weirdo.