It is time for Project Grit. We warned over the final weeks of the campaign that a vote to leave the EU would be traumatic, and that is what the country now faces as markets shudder and Westminster is thrown into turmoil.

The stunning upset last night marks a point of rupture for the post-war European order. It will be a Herculean task to extract Britain from the EU after 43 years enmeshed in a far-reaching legal and constitutional structure. Scotland and Northern Ireland will now be ejected from the EU against their will, a ghastly state of affairs that could all too easily lead to the internal fragmentation of the Kingdom unless handled with extreme care.

The rating agencies are already pricing in a different British destiny. Standard & Poor’s declared that Brexit “spells the end” of the UK’s AAA status. The only question is whether the downgrade is one notch or two, and that hangs on Holyrood. Moody’s has cocked the trigger too.

Just how traumatic Brexit will be depends on whether Parliament can rise to the challenge and fashion a credible trade policy – so far glaringly absent – to safeguard access to European markets and ensure the viability of the City, and it depends exactly how Brussels, Berlin, Paris, Rome, Madrid, and Warsaw react once the dust settles. Both sides are handling nitroglycerin.