Yet it is London that will gain from HS2 at the expense of the provincial cities, so where is the substance to the arguments in it's favour. Again, it is just mischief stared-up by political activists.
I don't doubt that London will benefit from HS2, but at the expense of other cities is quite a bold claim.
HS2 will probably mean that the will be up to 10 commuter services an hour over the Southern WCML, which will be a substantial amount of extra seats. Although that will only benefit one of the routes into London and won't mean that other routes won't be over crowded and need investment, such as CR2.
However it will also mean that Birmingham could see about 5tph, whilst Leeds and Manchester could see about 3tph. Although that isn't as many as London that is also a significant amount of extra capacity which would be fairly transformative, especially if the extra services run across the city effectively meaning that there are two services into the city centre for each path gained.
It is one of the reasons that I think that there's not a need for a significant Crossrail type project for those cities for the time being. However, that's not to say that they shouldn't see any investment. In fact with some extra funding it could allow a few more paths to be found to even further improve the benefits.
The other thing to consider is that HS2 is going to significantly reduce the number of people who are using XC to travel between Birmingham and Manchester or Leeds. That in turn will mean more seats on XC services for the stations between those cities not served by HS2 and therefore more capacity into those cities.
All of that is before you consider any changes in long distance provision, which is likely to be an improvement but probably not as significant as those listed above.
The problem is, even ignoring the HS2 services, up to 10 commuter services an hour into Euston will need significant improvements in capacity for onwards travel, which is where CR2 comes in. Without it Euston is likely to see significant overcrowding in its underground station, possibly to the extent that it is unsafe and the station sees periods of closers to stop it causing an incident (read death).
How many times have tube stations closed due to station overcrowding? I don't know, but I've witnessed it a few times (not associated with any large events, just near to popular tourist attractions like the national history museum) and I don't go into London lots, maybe a few times a month.
Yet other that when there's a major event I would doubt that many other cities see their stains closed on a regular basis in the same way that London sees its underground stations. The link below talks about over 500 closures of underground stations a year:
http://www.standard.co.uk/news/tran...-most-overcrowded-tube-stations-a3277706.html
It is why comparisons between overcrowding in Leeds and London on the mainlines isn't a fair compensation as you should also include the underground overcrowding to give an equal results.
It is why Crossrail is needed and why Crossrail 2 is also needed, as well as the other investment in the underground.