How important is recent Downing Street upheaval?

It’s been a week of abrupt changes in Downing Street with Boris Johnson’s Brexit negotiator – with Lord Frost elevated to the Cabinet and given responsibility for ongoing relations with the European Union.

Meanwhile, Johnson’s erstwhile deputy, Oliver Lewis, has quit as the man in charge of keeping Scotland in the Union – a role he was only given a fortnight ago.

It’s all reminiscent of the upheaval before Christmas, but does any of it matter?

We’re joined by Boris Johnson’s biographer Andrew Gimson.