Ah, Mandelson. Regarding upgrades as alternative, Adonis (who, being the minister to kick in the re-start electrification in Britain, can't be accused of ignoring conventional lines) said what I would have said:

Lord Adonis defends HS2 following claims it is an 'expensive mistake' | UK news | The Guardian

Adonis said the case against upgrades was proved by the £10bn upgrade of the west coast mainline, which "only delivered a fraction of the benefits of HS2".

The WCML upgrade was the perfect example of a major upgrade much more expensive than originally planned even after scaling down, but it's not the only one.

A cost increase by 10 billion pounds

British government adds £10bn to HS2 project | International Railway Journal

...This increases the so-called contingency fund for the project to £14.4bn.

Justifying the increase to members of parliament, the secretary of state for transport, Mr Patrick McLoughlin, said: "While I expect the final costs to be lower than those I have outlined... this is the right way to plan the project." The increased budget also takes account of design and environmental changes made to appease people objecting the project.

That said, I keep thinking that the HS2 project is over-priced.

_{*Lunatic*, n.
One whose delusions are out of fashion.}