You don't understand. Many countries in the UK are competing themselves to death in being "tax-friendly" to extremely rich companies and individuals. Even American rock stars are "located" in the UK, the Netherlands or wherever they can avoid taxation the most. Off course, this contributes nothing to either countries. To make matters worse, it opens up the possibility of all kinds of incomprehensible constructs that may even be less legal. But who knows? You'd have to know all the laws and all the deals with the tax authorities (which are, even though there are laws of government openness, secret).
Tax paradises are not only located in Africa and run by dictators. Off course, that is what politicians try to make us believe. Tax paradises are in a lot of cases our own countries. It is therefore quite hypocrite for a UK politician to condemn tax paradises or rich companies using them after these companies were lured to the UK for being a tax paradise in the first place.