It’s our first time on the Gwili Railway – thanks to a nearly-three year old boy obsessed with trains, or, more accurately, steam locomotives. We spend several hours pottering back and forth along the four mile track between the Railway’s current termini, Abergwili Junction and Danycoed, on two trains, one pulled by a steam engine, the other a crumbling but handsome old DMU.

Two thoughts occur to me as we amble along the track. The first is how lovely the Gwili valley is, with its steep-sided wooded hills, winding river and green valley bottom. It’s not a pleasure you can savour if you’re negotiating the A484 that shares the valley with the railway – a tricky road, narrow, slow and badly maintained, with many bends demanding close attention from the driver.

The other thought is what a thing it would be if you could travel by train past ‘Danycoed’ all the way to Aberystwyth. For almost fourteen years I travelled by car between Swansea and Aber, at least twice and sometimes four times a week. I never tired of the journey scenically, but it could be an exhausting experience, especially after a long day’s work, and it often struck me that the trip by train would be better for body and soul, and for the planet – my carbon footprint was ludicrously large in those days.

The line, of course, used to exist. Four trains ran in each direction each day, with some excursion trains coming direct from Paddington. Then, after about a hundred years of operation, Lord Beeching, one of Wales’s biggest vandals, targeted it for closure, so severing the only direct link between north and south Wales (for good measure he also closed the line from Afon Wen to Caernarfon). Passenger services ceased in 1965 and the tracks were ripped up in 1975. A bus service, currently the uncomfortable hourly T1 service, replaced the train: it takes almost two and a half hours, about the same time as the old train. In 2016, thanks to pressure from Plaid Cymru, the Welsh Government commissioned a study to look into how practicable it would be to reopen the line. This study, by Mott MacDonald, is still to be published (an earlier scoping report by a company called AECOM appeared in 2015). It would be very surprising if the Labour Government responds, when it does finally appear, in any other way than by shelving it.

There’s little doubt that the costs of reopening would be substantial, maybe £500m. Though about 97% of the original route remains intact, some it has vanished, some has been converted into cycle tracks, bridges have disappeared, and the existence of the Gwili Railway itself would be a problem. But then consider the cost and complexity of major rail projects elsewhere. The London Crossrail project will likely cost well over £20bn, and HS2, another England-only project likely to benefit London mostly, will cost over £60bn. A tiny fraction of the money devoted to one of these ventures (one of them, HS2, of dubious cost-benefit value) would serve to reopen the Aber-Carmarthen line.

All kinds of benefits could flow from the restored link. Life might return to towns and villages on the route – stations would be located at Llanilar, Tregaron, Lampeter, Llanybydder and Pencader – that have fallen on hard times. Tourism would see a boost. Long-distance travel would again become possible, with a truly integrated Welsh rail system. The environment impact of travel would be reduced.

One of the reasons the reopening will never happen, though, is that the vast majority of big capital spending on transport in the UK takes place in London and south-east England. The north of England has long complained fiercely about losing out to the south, but we hear very little about Westminster’s failure to fund major rail projects in Wales (the influence on government priorities of Alun Cairns, nominally Secretary of State for Wales, seems close to zero). This skewed pattern of funding reflects the grotesque privileging of London in UK economic policy, which in turn reflects the over-reliance of our economy on the City’s financial ‘services’ (maybe that will change a little once we leave the EU and the banks leave Britain). There’s little money left over for the rest of the UK.

There’s a second reason why the Aber-Carmarthen track will never see trains again. In Wales, Cardiff and its hinterland have become our own London, sucking capital spending as well as talent and other resources towards themselves at the expense of the rest of the country. Again, transport projects favour the south-east: the proposed rail network, misnamed the ‘South Wales Metro’, will primarily feed Cardiff, whose economy is already in need of little artificial stimulus. Most of the Welsh Government’s own transport budget will be swallowed up by the planned M4 ‘relief road’ (cost unknown: probably several billion pounds). Its building will result in immense damage to rare natural environments, and added pollution and global warming, thanks to the extra private vehicle traffic inevitably attracted to fill the new road. There’s little money left over for the rest of Wales.

In Scotland the people are more far-sighted and the politicians more determined: part of the old Borders railway, between Edinburgh and Tweedbank, was successfully reopened in 2015. It received far more use than the planners expected.

Here in Wales, though, my idle dream in the beautiful valley of the Gwili will almost certainly remain just that – a dream.