SOS PROJECTED ON CLIFFS - MUST ON SCREEN COURTESY LED BY DONKEYS A cry for help from anti-Brexit activists .... projected onto the white cliffs of Dover.
An exit from the EU without any transition deal is likely, many argue, to deliver a shock to trade, consumers - and an already suffering economy.
S&P is counting the cost.
The ratings agency says that since the 2016 referendum, the UK has lost 6.6 billion pounds - $8.7 billion - in economic activity.
Elsewhere, analysts point to the car industry as under threat - and other sectors dealing in cross-border goods.
But UK financial services also face crunch decisions on whether to trigger emergency plans.
SOUNDBITE (English) HANNAH MEAKIN, FINANCIAL SERVICES REGULATION PARTNER, NORTON ROSE FULBRIGHT, SAYING: "It's going to be a really big deal especially when firms have also made structural changes in the run up to Brexit.
So there's so many different aspects of the Brexit planning that need to come together to actually allow firms to be able to continue to do business.
It's really not an insignificant job that people have to do in the next next two weeks." S&P's numbers are slightly lower than a 600 million pounds assessment from Goldman Sachs.
But they also say that - if it hadn't voted for Brexit - the UK's economy would have been about 3 percent larger.
Surveys this week show the dominant service sector contracted in March for the first time in nearly three years.
Thursday's focus, though, was still mainly political.
As parliament continued its bid to shape events.
The debate in its upper house: whether to force the government to seek a Brexit delay - and prevent a no-deal departure on April 12.