Former Welsh Secretary Cheryl Gillan has called the London to Birmingham high speed rail project a terrible idea after her sacking from the cabinet.
Mrs Gillan was a known opponent of the HS2 scheme, which goes through her Chesham and Amersham constituency.
But she said she "doesn't feel like a victim" after her reshuffle removal.
Clwyd West's David Jones took her Wales Office job, and she said Prime Minister David Cameron made clear he wanted it to go to an MP for a Welsh seat.
She also raised concerns on the Murnaghan programme on Sky News that the coalition government was working too much to a "Liberal Democrat agenda" including what she called "time-wasting constitutional tinkering" - and too much of a focus on peripheral issues as a result.
She cited the AV referendum and Lords reform as examples, saying what was needed now was a government that was working together, joined up, and entirely focused on the economy.
Talking about her sacking, she said, "I've had two-and-a-half great years in government doing a job which I loved, and now that time has passed to hand that on to someone else.
"That allows me to almost go back to my roots, if you like, and to speak out about something that is affecting my constituents and my constituency, and that is this terrible HS2 project which the prime minister and my cabinet colleagues have known of my complete opposition to for a long time".
She said she was now "liberated" from collective responsibility to avoid criticising the proposed high speed rail link which is planned to go through her constituency, adding she saw it as "a very exciting time in my political life".
She said the plans were "very destructive to the environment" and not good value for money, adding that it was "so far in the middle distance" that it would have no impact on the current economic problems faced by the country.
Mrs Gillan attacked the two-and-a-half year timescale being put on the government's review of aviation capacity in the south east of England, saying she believed it could and should be completed by the end of this year.
Asked whether she was sacked because of strong rumours that she would resign from the cabinet if the HS2 proposals got the final go ahead, she said: "I think you've got to ask the prime minister about his reshuffle plans, although he made no secret either to me or to anybody else that he would eventually want a Welsh MP, an MP who sat for a Welsh seat, doing the job that I was doing, and what has been good for me is that my deputy David Jones, who is very able, has taken over, so there's a lot of continuity there."
She criticised what she called the "tittle-tattle" around the reshuffle, saying it would put off women in particular from entering politics, but she refused to criticise the Prime Minister for having a smaller proportion of women in the Cabinet as a result of last week's changes.
Among the media speculation surrounding the way the reshuffle itself was handled was a claim that Mr Cameron had delivered the news to Mrs Gillan that she was being sacked while he drank a glass of wine.
Asked to comment on this, Mrs Gillan said: "Can I just say that all this focus on the trivia of the reshuffle is not helpful to what this country is facing at the moment.
"I'm very focused, as I think is quite obvious, on making sure that what I have been doing behind the scenes in protecting the interests of my constituents from HS2 is now going to be in the open and I think that's very important."