Have you noticed how many siren voices are suggesting that Britain rescinds Article 50 to buy time? The Irish Taoiseach, Leo Varadkar, tells us that it is in the UK’s gift to avoid a no deal Brexit and buy “more time to decide what it wants” We have Sir John Major saying “We need to revoke Article 50 with immediate effect. The clock must be stopped. It is clear we need the most precious commodity of all: time.” Versions of this can be heard elsewhere. But it’s legal nonsense, for reasons that are not properly understood.

The ECJ did not give us carte blanche to revoke the notice and then re-issue notice as we see fit. Words matter, and each of its words has a legal definition.

The recent ECJ ruling which said that we could unilaterally revoke Article 50 placed some fairly severe restrictions on the UK. For starters, for a revocation to be valid it has to be both ‘unequivocal and unconditional’. If the UK did as Varadkar and Sir John suggest and revoked Brexit for tactical gain, the decision would be wide open to legal challenge.

This would theoretically give the ECJ, as a political court, enormous power in any negotiations. At any point they could declare that the revocation was invalid and kick the UK out of the EU, without giving us any time to prepare for no deal. It would leave the country over a barrel. If the UK were to revoke just to buy more time, then that will be seen as “equivocal” or probably “conditional”.

If the ECJ rules a revocation is either, then it is invalid. So we’d be booted out. And if the ECJ rules a revocation invalid after 1st April 2019, then the UK has left without a deal from the day the ECJ decides to give that judgment. In theory, that means the ECJ could threaten our economy when it felt like it. In practice that means the EU can force the UK to agree anything at all (to prevent that happening).

The only way the UK can confidently revoke notice is in the full knowledge that notice could only ever be given again IF there is another referendum, another vote to give notice and another notice.

If we give notice to revoke then, purely to protect ourselves, we must say that the referendum in 2016 was invalid – and wipe out the wishes of 17.4 million people with one stroke of the pen.

But doing so also has to satisfy our “constitutional requirements”. The Gina Miller case last year established that revoking the notice at least requires a vote in Parliament and primary legislation. But it could also mean, because a referendum was required to submit the notice you are trying to cancel, that another referendum would be needed to revoke it. The dangers of giving a revocation that is vulnerable to any challenge are worse than an anticipated no deal. It’s difficult to underestimate the tension as we all sat around waiting for the ECJ to tell us if we had accidentally left with no deal months earlier, because our revocation was invalid in their eyes.

It’s unlikely that either Varadkar or Sir John properly understand this, which is understandable. Rulings of the EU’s court are not intended to be understood; the ECJ exercises power through deliberate ambiguity.

But it boils down to a simple point. Revocation of Article 50 is for life, not just Christmas