Well the splitting of HS2 into two phases pretty much precluded the research of a route option loosely along the Great Central, though sections are used or paralleled by both stages (Stage 1 at Aylesbury and Stage 2 north of Nottingham). Upon checking, minimum curve radius was one mile except in cities, and there are a couple of cities crossed in the middle (Rugby, Leicester, Loughboro, Nottingham), so mayor deviations from the original route would have been needed for high-speed use.

My own take on the route is that they should have focused on following existing transport corridors from the onset (they did consider on sections after the public consultation).

key marginal constituencies which need to be flattered

The flattening I find in Wolmar's article is in London:

All the opposition has so far focussed on the Chilterns, but it is Camden council tenants who are most affected with the demolition of 600 homes and possibly more.

As for Wolmar's op-ed, you quote a part which is mostly rhetoric, while he makes several more focused arguments in the article. I react to some at a more general level:

• I have nothing against the criticism of various parts of and studies for a project, but that's something else than heaping up everything (including the utterings of "several think tanks" "on the Right") in all-or-nothing opposition. My reaction to a number of issues he raises would be "that's a problem, change the plans". My reaction to the increased budget was to look at the benefit/cost estimates and see that even if all of the contingency would be spent, they would remain above 1.
  
• Also, total sums are impressive, but the question is, over how many years.
  
• What bothers me most is the contrast with local public transport spending at the end. Yet again, I say they aren't rivals but both of them are rivals of other modes: one shouldn't ask "HS2 or commuter rail", but "HS2 or airport expansion" and "light rail or car". Furthermore, it's not like nothing is being done on the London local transport front. Much more should be done. In particular, relieving commuter train congestion would need a long over-due RER-style system, but even what's done on that front has gotten similar opposition (Crossrail 1). BTW, consultation for Crossrail 2 started.