Gus O'Donnell | Brexit is a massive venture. There’s no way these changes will happen smoothly

Leaving the EU would have been enough of a challenge for a strong majority government – there needs to be clear political leadershipDavid Davis has described elements of his job leading the UK out of the EU as “making landing on the moon look simple”. My successor as cabinet secretary and head of the civil service, Sir Jeremy Heywood, has described Brexit as “the most complex challenge the civil service has faced in our peacetime history”. And now the head of the Na