Plenty of money was spent to try to convince the more gullible segment of the UK populace that their future would be rosy if the UK could go it alone, and a lot of that came from the wealthiest segments of the country. The financial services industry was worried that Frankfurt or even Amsterdam or Paris might take the crown, which for the most part hasn't happened.
And with multi-nationals such as Shell moving to the UK the balance is shifting further away from where it should be, now the UK will act as a de-facto tax shelter in all but name because it can afford to offer these companies great terms, after all, they have nothing to lose.