This was later ruled out, but could now be back on the table.

The announcement of the precise route for phase 2 is already running about a year behind schedule. It was to have been decided last autumn, but HS2 now says it will be announced in “autumn 2016,” subject to the Heywood review.

Whitehall sources said the preference was to try to “re-establish control,” if possible, over the costs of the existing scheme without major cuts to its scope.

In real terms, HS2 will cost up to nine times more per mile than the French TGV high-speed lines, according to the House of Lords’ economic affairs committee.

One key opponent of HS2 said he had recently been called in by senior Treasury officials to tell them his concerns about the scheme.

“They said they wanted to see me urgently. They even offered to come to me,” he said.

“They said they were fully in favour of HS2 but they were worried about it. They were listening very intently when I said that the project was out of control.”

HS2 has already spent more than £1 billion before the legislation to build it has passed through Parliament and before a single foot of track has been laid.

Large sums of money have been paid in “facility fees” to local residents for allowing access to their land or property. One opponent of HS2 said she had received 17 separate visits, collecting payments of between £160 and £1,000 for each visit.