The business case is there - ??? That is very questionable now, particularly with the desirability of reducing travel from a "green" perspective, and with the ability to increase the use of electronic meetings (both for business and social communication) accelerated by the Covid epidemic. The eastern arm, and the western sections north of Crewe, do not have the same case as phase 1 and phase 2a to Crewe in terms of providing extra capacity, as the existing lines are not so congested. and the number of tph that will run on them will be far less than on phase 1 and phase 2a as far as Crewe.
It's very doable - ??? Yes, but not "very" - it will cost more and be more difficult to achieve than elsewhere. Most other countries are less densely populated, so the destructive impact of new lines cutting across the country is less. Planning controls are also less and governments can railroad projects through. The H&S culture is also less of an issue. England is not China.
It's a successful model in other countries - ??? Even ignoring China, other European countries are wealthier and much bigger, and distances between cities are much greater than in England. In terms of speed, all that is required is to reduce journey times from London to all cities with a population >100k in England to less than 3 hours to kill off intercity air travel completely, and ideally to <2 hours for the 4 major cities in Northern England (Leeds, Liverpool, Manchester & Sheffield). HS1 and HS2a to Crewe will achieve this for Liverpool and Manchester, and also for Sheffield even if the eastern arm isn't built and trains are routed via Derby and the existing MML. It is possible to run non-stop from King's Cross to Leeds via the ECML in 2 hours, and some small improvements to that line should enable this to be achieved on a regular all day basis.
I have not mentioned Scotland, as I expect that (all being well) it will be independent and have re-joined the EU by the time HS2 opens, and international passenger rail travel, particularly across a hard border, is typically much less than that within countries without barriers on the border. Elsewhere in Europe, international passenger rail travel is continuing to decline even if domestic rail travel is holding up.
So let's commit to building the damn thing - ??? Not the typically English way of doing things!
Especially since phase 1 is underway - ??? That is not a reason to build HS2 lines north of Crewe or the eastern arm. The English financial situation is likely to head in the same direction as Argentina post-Covid and post a hard Brexit, with unsympathetic rulers in Beijing/Berlin/Brussels/Washington. It is very questionable whether building the bits of HS2 where construction has not yet started is affordable.
The business case is there :
-you're misguided if you think that travel is permanently reduced because of covid. Trust me, in 6 months no-one will be saying this.
Let's entertain the possibility though, even if it is, the climate change crisis leaves us desperately in need of modal shift. Not just climate change actually, pollution and congestion are issues that affect us now.
It's very doable:
-It actually doesn't cost more than lines elsewhere. The only reason it seems worse than comparable projects in Europe is because they tend to be built in phases, with station upgrades done as seperate projects.
Dense, rich countries with high H&S standards such as South Korea and Japan have managed to do it, why not us?
Successful model in other countries:
-Honestly, pointing at specific journey times kind of misses the point. HS2 is primarily about capacity, both on the line and the existing network. The speed is a byproduct of this, and also enables us to use a single route coming out of London, to replace three mainlines.
HS2 will, however, decrease journey times to the South West massively, a big driver of domestic air travel in the UK. My uni friends who live down there very often fly/drive from Manchester because the train is overcrowded, smelly and slow.
Plus, HS2's biggest benefit is on the existing network, that's more commuter, regional and freight (don't forget about freight!) trains, that will help to replace the road traffic that currently chokes our cities.
Scotland
Those comments belong in the speculative section, realistically. Even if Scotland leaves, remember the cities like Newcastle up on the east of the country, they'll benefit from HS2, too, with reduced journey times to Birmingham and London.
Not typically the English way of doing things:
Yes and that has left us with a more overcrowded, expensive and slower network than our friends on the continent have.
The economic argument:
It's actually a fallicy as to wether we can "afford it". The reality is, we cannot afford not to spend money on infrastructure. Money spent on HS2 will help to kick-start the economy Post-Covid and all the well paying jobs created by it will move our economy forwards, and centre us as a hub for skilled manufacturing.
Countries like Germany and Japan have not become so successful because of some inate cultural differences. The difference between them and us is they have invested in Infrastructure, Health and Education to help facilitate good economic growth and a high quality of life for their citizens. (which is what any good economy should aim to provide)
It's time Britain did the same. We're the 5th largest economy in the world, but frankly looking at the state of the country, it does not feel like that.