Not being able to extend the transition period means that, at a stroke, UK's negotiating position is profoundly weakened

UK will have to accept what EU offers, and get Johnson to declare it a triumph

It also necessarily limits options available

A few months is not a long time

Since 31 January 2020, UK has been artificially protected from almost all the effects of Brexit by the transition arrangements

This provided for a false sense of continuity

The abrupt removal of all those arrangements on 31 December 2020 is now the default position

There will, no doubt, be a deal or deals by 31 December 2020

Minds will focus, and EU will look to protect its interests as best it can

But understanding this default position means you understand the power dynamic for the months ahead

And UK government just let this happen