It is estimated that 500 people come to Britain each day rather leave. So where are these people going? Why are people being told that their towns' are getting smaller when they are not? The clues are there if you know where to find them. Walk around Slough's estates and look in the back gardens. There are buildings here you are unlikely to see anywhere else in the country. These are Slough's 'sheds with beds. In some areas, row upon row of them. Lines of small houses tucked away behind the main homes. And inside them are the people who are transforming this place. A new workforce.