Dr Julian Lewis: Given that the EU never makes its final concessions until just before any given deadline, what could possibly be gained in 24 months that could not be gained in 21?

[The Prime Minister: The purpose of the backstop is to cover the circumstances in which the future relationship cannot be put in place by 1 January 2021. One example might be if it has not been fully ratified by all the Parliaments in the EU that need to ratify it – the process is going through but has not been completed by the end of December 2020. That is why the backstop is in the withdrawal agreement. It is an insurance policy for that period.]