FROM a pipe dream of rail campaigners to the centrepiece of the UK Government's transport policy, high-speed rail has generated both ardent enthusiasts and vocal opponents.
Love it or loathe it, its impact on bringing the south of England closer to the Midlands and northern cities of Manchester and Leeds is likely to be considerable over the next two decades.
But until now, the prospects of Scotland participating in such a transport revolution appeared remote at best.
Plans to build a first phase between London and Birmingham would have a negligible effect for Scotland as passengers would actually navigate the northern leg of the journey, on the West Coast Main Line, at slower speeds than is currently achieved by the tilting Pendolino trains which can accelerate better around its many twists and turns.
The reason for this oversight is because the justifications for building such an expensive piece of infrastructure are very different in Scotland than they are in England.
South of the Border, the argument rests on providing extra capacity for a horrendously overcrowded rail network, allowing growth not just for high-speed services but for other trains on surrounding lines.
With the West Coast Main Line rapidly reaching its capacity between London and the Midlands, new track is desperately needed. And so, the thinking goes, if you're going to build a new line it may as well offer faster journeys.
By contrast, Scotland does not have the population density of Birmingham, Manchester and Leeds or suffer the same overcrowding on transport networks. So on these grounds, the case for high-speed rail is weaker.
In its favour, a line connecting London to Glasgow and Edinburgh would offer enormous potential for attracting new passengers who currently fly, with research suggesting that train journeys have to be under three hours to be attractive. A train from Glasgow or Edinburgh currently takes around 4.5 hours to reach the UK capital.
Not only would faster journeys bring significant economic benefits, there would be a huge environmental gain in cutting emissions from replacing domestic aviation with train travel, which is less polluting.
A study by infrastructure operator Network Rail also backed completion of a route all the way to Scotland due to the potential for higher fares paid on the long-distance routes.
Despite the sabre-rattling that characterises much of the relations between Westminster and Holyrood, dialogue on high-speed rail appears to have been more fruitful.
Today's announcement by Alex Neil follows months of behind-the-scenes discussions between transport minister, Keith Brown, and former UK Transport Secretary Philip Hammond.
This culminated in an deal that the Scottish Government would, in principle, fund any new infrastructure north of the Border, with the Department for Transport paying only for the English section.
That still leaves a daunting bill – last estimated at around £15 billion – for a Scottish leg. But ministers can probably take comfort from the knowledge that, though they may get the train rolling, they won't have to find the money any time soon.