Brexit: what is the UK's backstop proposal?

The whole of the UK could remain in the customs union for a time after transition in order to prevent a hard border in IrelandBoth the UK and the EU are determined to avoid a hard border – physical infrastructure, officials, checks – between Northern Ireland and the republic after Brexit. The government believes the key to doing this is a comprehensive free trade and customs agreement, but the EU fears Theresa May’s red lines of leaving the single market, customs union and ECJ