Sir Nicholas said there had been a "grotesque injustice"
Sir Nicholas Winterton has angrily denounced plans to reduce first-class travel by MPs - telling the BBC he needs "quiet" and privacy to work.
The veteran Tory MP said there was a "totally different type of people" in standard-class train carriages.
He also said it was a "grotesque injustice" that the expenses system had been "misrepresented" by the media.
A Tory spokesman said Sir Nicholas's remarks were "the out-of-touch views of a soon-to-retire backbench MP".
"They do not in any way represent the views of David Cameron or that of the Conservative Party and should be treated as such," the spokesman added.
Macclesfield MP Sir Nicholas, who is standing down at the general election, spoke to the BBC following an interview with Total Politics magazine, in which he said restricting first-class travel left MPs "below local councillors".
'Need a seat'
Sir Nicholas, an MP since 1971, told BBC Radio 5 live that MPs worked "extremely hard" and used the time travelling between London and their constituencies to work.
But he said to do that they had to have a seat - something you could not always get in standard class.
And he said: "If I was in standard class I would not do work because people would be looking over your shoulder the entire time, there would be noise, there would be distraction."
He added: "They are a totally different type of people.
"There's lots of children, there's noise, there's activity. I like to have peace and quiet when I'm travelling."
Sir Nicholas said he was not saying people who used standard class were inferior but that, in general, they were not working while travelling.
He said he was angry because allowances had been "misrepresented" as expenses, something that was a "grotesque injustice".
Sir Nicholas and MP wife Ann Winterton, who is also standing down, faced criticism for claiming rent of £20,000 a year on a flat they transferred to a family trust after paying off the mortgage.
Sir Christopher Kelly said MPs should ensure value for money
A seven-month inquiry into MPs' expenses last year recommended a series of changes to overhaul the system.
Among the proposals, currently under consideration, is one saying MPs should "be permitted to claim for first-class train travel for longer journeys where issues of space or privacy in which to work make this appropriate".
But it says MPs "should always ensure that value for money for the taxpayer is provided when making travel arrangements".
'Sitting in judgement'
It also recommends that they should only claim for economy class flights within the UK or Europe and stop claiming for first class travel for their families.
Sir Nicholas also singled out Sir Christopher Kelly, chairman of the committee on standards in public life, and Sir Ian Kennedy, head of the new Independent Parliamentary Standards Authority, for criticism.
"The people who are sitting in judgement of us not only travel first class themselves, but in the main are on at least twice the salary of members of Parliament."
But his remarks were criticised by other MPs. Labour's John Mann told the BBC: "It is total nonsense that MPs, particularly in a recession, should regard themselves as a different kind of species.
"MPs need to get out of this mindset that, somehow, we are above the general public, that we are special. Travelling second class keeps you in touch with the general public."
'Hit the buffers'
Liberal Democrat MP Norman Baker told the BBC it showed the Conservative Party had not changed: "They still think they are a class apart, they still think they are privileged, they resent the idea that they should be subject to the same controls as everybody else."
But Tory Party chairman Eric Pickles wrote on the Twitter micro-blogging website: "Sir Nick has hit the buffers on his rail demand - a protracted period in the Standard Class quiet carriage would be welcomed by everyone."
Sir Nicholas received some support locally - Mark Asquith, a Conservative councillor in his constituency, told the BBC: "He's absolutely right, first class is quiet. It's a good place to work and that's what he's doing. We pay him an awful lot of money. I don't want him wasting his time on the train."