One portent of the decline, and eventual collapse, of the Roman republic was the demand from ever less impressive generals for ever grander triumphal processions to mark ever more minor military victories.

I do not think British democracy is about to collapse into tyranny. Yet there is more than a whiff of decay about the way in which Conservative government ministers, from Theresa May down, claim to have pulled off a strategic masterstroke in agreeing the outlines of a “transition treaty” covering the 21 months that will follow Britain’s planned exit from the EU at the end of March 2019.

From money, to law, to immigration, the agreement looks like anything but a victory for ministers who promised the earth as part of the Vote Leave campaign.

The core claim of the Leave side in the referendum was that quitting the EU would lead to a financial bonanza for Britain. But the agreement is closer to the sort of thing borrowers in trouble sign to consolidate their debts, than to a winning Euromillions ticket.

Not so long ago Boris Johnson told the Commons that the EU could “go whistle” for a divorce settlement but now the government have agreed to pay not just for existing EU programmes but for everything from civil service pensions to Euratom assets left stranded here upon Brexit.

At least this bit was not news, only last week the chancellor published the OBR’s estimate that the total bill – payable in instalments up to 2064 – was likely to come in at about £40 billion. However, that too could rise if the pound sinks – because this week’s agreement makes it clear that all bills are to be settled in Euros.

The bill is only the most visible concession. On almost every negotiating point this agreement represents a retreat because of the unsustainability of the red lines the prime minister issued at the behest of Jacob Rees-Mogg and co.

The ECJ could be issuing mandatory instructions to British courts well into the 2030s, migrants and their families get full rights in the transition and beyond, while the retreat on fisheries threatens to provoke the Conservative right into blocking the whole thing: even if it has entertained the nation with the sight of grown men messing around on boats in the Thames.

On the really difficult issues, particularly the question of the Irish border, the agreement says nothing at all: the government seems to be hoping something will turn up but has no idea what.

All of this though is, in a way, obscuring a bigger story. This is supposed to be about a transition in which we implement the changes necessary to prepare for life outside the rules and protections of the EU.

It is meant to avoid British exporters and consumers being hit by a chaotic Brexit: buying us time to prepare for a mapped-out future.

But it will be none of those things because it is a transition to nothing. Realistically there is no chance of a comprehensive agreement on post-Brexit relations between Britain and the EU being agreed before March 2019. We are getting a transition to free fall off the European escarpment.

If we are lucky we might have agreed a framework for new relations by the time the transition has ended.

But trade deals take time and even a compressed transition period is hardly likely to be adequate for businesses with long and deep European supply chains.

Much better, surely, to seek to extend Article 50 and negotiate a deal while we are still members of the EU and still have full voting rights on the EU’s ongoing business.

That might deny the Brexiters their empty triumph.

But it has to be better than walking off the cliff and hoping for the best.