Next Saturday, tens of thousands of Remain supporters are expected to descend on London for what is billed as the biggest ever pro-European protest march.

They will demand a “people’s vote” on the final Brexit deal - in other words a second referendum, with the ultimate aim of stopping Brexit.

With just 286 days to go until Britain formally and legally leaves the EU, it might be assumed that their angry cries will be carried away on the wind.

Yet there is a growing nervousness in Downing Street that a moment of genuine danger for the Brexit process is just days away.

A highly-organised pro-European machine, lubricated by the cash of the financier George Soros, believes it is closer than at any time in the past two years to reversing the Article 50 process triggered by Theresa May in March last year.

A single word inserted into or removed from a seemingly obscure amendment to a Government Bill could be the key that unlocks their dream of eternal EU membership.

The Telegraph has learnt that aside from the very real fear that Parliament could give itself the power to take over or even halt the Brexit process, another threat lurks in Westminster: that judges in the Supreme Court could end up deciding the issue instead.