The tycoon who founded International Workplace Group (IWG), the world's largest shared office provider, is hatching a secret plot to spin off its US business into a separately listed company in New York. Sky News has learnt that Mark Dixon, IWG's chief executive, is in talks with investment banks about creating a standalone business that would become a publicly traded rival to WeWork, the US unicorn targeting a valuation of about $50bn when it floats in the coming weeks.