WATCHING TV at the weekend, I caught Nick Clegg declaring that the HS2 high-speed rail link would "heal the north-south divide".

Not for the first time in this life, I wondered what happens to geography when you sit in a London studio. By Mr Clegg's reckoning, this is being written somewhere to the near north of north.

From an English perspective, of course, the Deputy Prime Minister's sense of a country was perfectly accurate. The heart of his north is Newcastle; its last outpost is Berwick. Just up the A1 lies a border, clearly defined. But from a British point of view?

Where HS2 is concerned, they might as well erect the border posts that are supposed to be the secret desire of all Nationalists. What is being defined by the London Government as a major infrastructure project designed to benefit an entire country – "vital for Britain", says David Cameron – is not coming our way for a generation at least, if at all.

This is no small matter. The £33 billion cost of HS2 might be a sum guessed at in the last days of a Labour government. The 100,000 jobs promised – a suspiciously round number – might be a figure conjured from the air. The economic benefits foretold – £2 for every £1 spent, say promoters – might be dubious in the extreme. As things stand, Scotland will see next to nothing of any bounty.

Why is that, exactly? You could resort to an SNP attitude and speculate that we'll get nothing extra from England's taxpayers until constitutional ferment subsides. You needn't go that far. The better conclusion is that Scotland just isn't important enough, or populous enough, to merit a high-speed connection with the rest of the UK as a matter of urgency.

If your honest desire is to bind Britain together this is, of course, illogical. If you truly wanted to rebalance the British economy, if you desired honestly to address the imbalance between London and other parts of the island, you would start building your line in Glasgow or Edinburgh and work south. But these things, patently, are a matter of perspective.

One of the London newspapers claimed yesterday that HS1, the link between St Pancras International and the Channel Tunnel, "cost £7.3 billion to build and is now expected to produce a total economic benefit of £17.6 billion". If true, that's a notable achievement. Since I live in a country alleged to depend on the south's subsidies, however, I am entitled to ask who gets the considerable benefit of that major investment.

For Scotland, these are practical issues. Should I want to go from Edinburgh to Paris (that would be most days) the "best total journey time" quoted by Eurostar is 7 hours 46 minutes. Apparently I would have to allow 1 hour 7 minutes "stop over" between King's Cross and St Pancras International. If I lived in south Yorkshire, on the other hand, I could take a train from Sheffield direct to the Eurostar hub.

You could call it a small grumble, but it is part of a tale that has been going on for decades. Blameless Sheffield, already linked to St Pancras, is part of the HS2 scheme, and will get a new station into the bargain. Places that seem, on the map, to be rather closer to London than Scotland will be brought closer still. People in those places will not pick up the entire £33 billion bill, however.

The irony in all of this is that large parts of England, rural and urban, seem less than keen on HS2 and the swathe it will cut through the landscape. Environmentalists, wedded to rail, have been muted in their criticisms, but the reasonable view appears to be that, given the impact of construction, the scheme will be carbon-neutral, at best.

The final cost is anyone's guess. As "a vital engine for growth", in the Government's words, HS2 will be an unproven case for a long time to come. A split line that won't reach "the north" finally until 2033 does not count as the sort of infrastructure project that will answer immediate economic needs. Equally, the plans take no account of changing work habits over the next 20 years. HS2 cannot be held up, meanwhile, as the answer to the network's capacity problems because no-one can say what those problems will be come 2033.

Still, cities in the English north have clamoured for an improved connection. Dispassionately, they count as Scotland's competition in these matters and yet they already possess superior transport links. HS2 threatens to allow those of us with long memories the chance to revisit Carstairs Junction. It threatens to cut off Dundee, Aberdeen, Inverness and the true north from direct services to London. And this is "vital for Britain"?

Wales, it needs to be said, has parallel concerns. HS2 is advertised as one of those regeneration efforts for the benefit of "the regions", but for the purposes of this exercise Britain is being divided into core – London, Birmingham, Manchester – and periphery. The chances of HS3 reaching places of peripheral political interest before it is overtaken by technological change are remote indeed.

Some who have studied high-speed rail in Europe argue, in any case, that connecting a capital with its provinces does not guarantee regeneration. The evidence from France and Spain for such an effect is said to be thin. In other words, cutting the journey time from Manchester to London in half might do the latter more good than it does the former.

Nevertheless, the opportunity will be Manchester's to seize. Scotland, as things stand, is being cut out of the loop entirely, with the promise of a slightly quicker service eventually for those taking trains from Edinburgh and Glasgow. Anyone in the actual north, already obstructed by the Central Belt, is liable to be worse off. Yet HS2 remains an avowedly British project, launched – with no sense of irony or embarrassment – in the national interest.

You could make a fine Nationalist case against this naked discrimination. The trouble is, independence would not solve Scotland's transport problem.