Leading article: We're shown up again. For once, Britain should follow the French

The French government has just announced approval for a new high- speed rail link east of Paris, cutting journey times to Strasbourg by an hour and a half. That's France: a socialist government, dreams of glory and tons of Euro-sentiment (the train, said a minister would "optimise links between the axes of the Rhine and the Rhone"). Transport officials in this country don't talk that way. But that doesn't stop them getting out of their depth. This country, too, has its share of grand projects which run over time and over cost - the Jubilee Line in London being the most egregious current example. Yet we lack transport imagination, understanding transport infrastructure as a whole, planning and thinking strategically. Especially now that the plan for building a fast link to the Channel Tunnel has collapsed. It has to be revived, cherished and reconfigured.

Forget the nominal transport minister, Gavin Strang. The man on the mat is John Prescott, Secretary of State for Environment, Transport and the Regions. Commiserations. He is, by nature, a big spender who is marooned in a Cabinet where financial rectitude rules. He is a big-picture man, yet only in the minutest phraseology of intricate contracts is the dream of public-private financial partnership ever likely to be realised. It is he who has to put together transport and sustainable development: who but John Prescott is to see that new rail termini at St Pancras, not to mention Stratford could serve to jump-start that "brownfield" building which is supposed to be the alternative to dumping concrete on the green belt.

Fate - the paucity of imagination and conceptual confusions of the Thatcher and Major government, to be precise - has stacked Mr Prescott's in-tray high. The clock is ticking down to formal revocation of London and Continental Railways' contract. Replacements are knocking at DETR's door, eager to state terms. But they all involve substantial extra public money, either directly (Eurorail is asking for more than pounds 2bn, most of it upfront) or indirectly (Railtrack would like to negotiate a cross-subsidy from higher track usage charges elsewhere). Meanwhile, the Government faces the prospect of re-acquiring formal ownership of Eurostar, the company running cross- Channel services; public ownership is also the option if railway franchisees fail to live up to their contractual obligations.

Behind all this lies a term unstated in all the rhetoric about Private Finance Initiatives, contracting-out and privatisation. It's what happens when private capital fails. Theoretically, contracts can be re-let and new providers brought in. But what happens in the meantime and what if the new contractors use the threat of a break in service to blackmail the state? That is John Prescott's position now.

The Government could, it is true, abandon the idea of a fast link to the Channel. With it probably goes the profitability of Eurostar, a boost to economic growth thanks to better through-routes from Birmingham, Manchester, Scotland and Ireland, let alone the specific benefits to London's East End of making Stratford once again a great transport node. But how much additional investment of public money is all that worth?

The answer, in principle, must surely be no less than the pounds 2bn figure being bandied around - albeit payable over a period of years, which would not need to start till after that magic hour on 1 April 1999 when Labour's commitment to Tory spending plans comes to an end. But Mr Prescott and the Treasury ministers he eventually has to convince know there is a more important question than how much money. It is how to assure the state that private sector partners are reliable, at least more reliable than the members of the LCR consortium. Their ranks include two existing rail franchisees, National Express and Virgin and if, after what has happened, their conduct of their railways is not brought under the closest inspection by ministers, they ought to be. Richard Branson may have emerged from the libel courts a people's hero; he may be Mr Blair's most acceptable capitalist face. But Mr Branson the blond controller needs policing.

Once, when Labour first came to power in this country, the talk was of the state taking over great chunks of private capital. During the Thatcher era, private capital could do no wrong - the best the state could do was retreat. We surely now know better. In large-scale infrastructure projects neither the state nor private capital is superior as financier or manager. But we have learnt the hard way that the state is indispensable, as projector, guarantor and backstop. Exactly how much the Government should spend on the fast link to the Channel is up for negotiation, but it can and should commit itself now to the principle of full-blooded participation.