Office lights in some corners of Westminster were on much later than usual last night.
Why? Because ministers and officials, just like so many others, were watching the telly to see what US President Donald Trump would have to say, the Business Secretary Jonathan Reynolds among them.
The president, brandishing a giant rectangular piece of card packed with the new tariff increases, unleashing waves of anxiety across factory floors, boardrooms and government ministries the world over.
Folk in government in the UK had picked up a sense of the mood music – a sense that the UK was “in the good camp rather than the bad camp” as one figure put it to me – but they had no idea in advance precisely what that would mean.
We now do know what it means – a 10% tariff on the UK’s exports to the US.
I detect a sense of relief among ministers, but make no mistake they are not delighted – the tariffs imposed on the UK will have significant effects, and the tariffs on the UK’s trading partners will have a profound impact on jobs, industries and global trading flows in the weeks, months and years to come.
It will be “hugely disruptive,” as one government source put it.
There is an acute awareness in particular about the impact on the car industry.