Work on HS2 is finally due to start next year. And those whose housing will be affected have dominated the headlines. But what will it mean for business? For some it seems a huge opportunity if high speed rail kick starts much broader regeneration. Other businesses face major challenges during construction, or fear they'll lose out when the new railway changes the way people work. And what does it all tell us about how the UK copes with major infrastructure? Maryam Moshiri visits Sheffield and north London to test business opinion.