1: INDEFINITE BACKSTOP

WHAT IT SAYS: “The Protocol [backstop] comes into force on the conclusion of the transition period and is intended to apply while negotiations are continuing for an agreement that supersedes it... The Protocol would endure indefinitely until a superseding agreement took its place.”

WHAT IT MEANS: The backstop will last until EU and UK negotiators agree a trade deal, or come up with a better technological solution to stop a hard border between Northern Ireland and the Republic.

WHY IT MATTERS: Leave-backing Tory MPs have always claimed the UK could become stuck in a backstop without end: this confirms it.

2: QUITTING BACKSTOP

WHAT IT SAYS: “The current drafting of the Protocol .. does not provide for a mechanism that is likely to enable the UK to lawfully exit the UK-wide Customs Union without a subsequent agreement.”

WHAT IT MEANS: We can’t just up sticks and leave the backstop, we are trapped. It doesn’t matter how long talks are going on or even if they collapse. WHY IT MATTERS: Reclaiming UK sovereignty was, for some Brexiteers, at least as important as cutting immigration. This legal advice says the UK cannot just walk away from a backstop arrangement so, Leave supporters argue, how is Britain “taking back control”? We would be tied indefinitely.

3: NORTHERN IRELAND

WHAT IT SAYS: “NI remains in the EU’s Customs Union which means goods can pass from NI to Ireland without border checks. GB is in a separate Customs Union with the EU. Goods passing from GB to NI will be subject to a declaration process.”

WHAT IT MEANS: Northern Ireland will be carved off and treated differently. Goods moved between the mainland and Northern Ireland will be checked, so the UK’s single market is smashed apart.

WHY IT MATTERS: Theresa May relies on the Democratic Unionist Party’s 10 MPs to give her a Commons majority. Hardline unionists will not back moves that make NI different from the rest of UK.