The UK cannot crash out of the EU without an agreement because it would lead to immediate social and economic breakdown with air, sea and land transport systems grinding to a halt, industries closing down overnight, UK citizens marooned without rights or legal status in the EU and much more.
Hence, without an agreement to new arrangements with the EU, the current arrangements will persist whether by postponing the UK exit under Article 50 or by the UK and the EU agreeing an interim ‘standstill’ under which the UK exits membership under Article 50 but remains bound into and governed by the EU’s laws and institutions but without a say in what those laws should be or how those institutions should operate.
Because crashing out is not an option in the real world, any postponement or interim arrangement would have to continue until a final agreement was concluded. The EU would have no reason to make such a final agreement as doing so would harm the remaining members who would, amongst other things, lose the benefit of the UK contribution to its budget, access to the UK market and Ireland, in particular, would lose a vital trade route into continental Europe through the UK mainland. Indeed, it is impossible to imagine how Brussels would persuade the remaining member states or the European Parliament to vote to move on from an arrangement that benefits them to one that would harm them. The result would be an indefinite limbo.
It is time for the Brextiers to admit that Brexit was never a real option and to demand that the government call the whole thing off. The risk otherwise is that, rather than gaining in UK sovereignty and democratic accountability, the UK will become what Mr Rees-Mogg has accurately described as a “vassal state”.