As crunch time approaches, we talk through some worst-case Brexit scenarios: for the government, for the economy, for Remainers, for Europe.  Have the negotiations been a humiliation for Britain?  Is the Tory Party facing an existential crisis?  And what might go wrong if the marchers for a 'people's vote' got their way?  Plus we speculate about what a no-deal Brexit would mean for Britain's service economy.  With Diane Coyle, Helen Thompson and Chris Bickerton.