Mr Nicholls sought to defend his actions - which were within the rules until they were changed in last Monday's Commons vote - by suggesting the only difference between him and the two MPs disciplined for accepting "cash for questions" was that they were prepared to act for concerns they "knew nothing about".
Mr Nicholls, in a letter to World Water Services obtained by the Sunday Mirror, promised to try to persuade ministers that their departments should buy its products in return for a shareholding if it made a profit. The new rules ban advocacy on behalf of interests from which MPs could benefit in future.
Mr Nicholls, MP for Teignbridge in Devon and a former Environment Minister, insisted he had received no money and declared his unpaid interest in the company, formed to sell a water purifying system. Mr Nicholls resigned as adviser to WWS after Monday's vote.
John Prescott, deputy Labour leader, condemned Mr Nicholls. "His boasting of his influence is quite nauseating, while his hopes of a fast buck as a result of it could not be clearer," he said.
Mr Nicholls's letter appears to be a textbook example of the kind of lobbying which would have been banned even under the more limited proposals backed by John Major - and defeated by the opposition and 23 Tory rebels on Monday.
Mr Nicholls wrote: "I can provide access to departments of state. The problem is that if a private person or company writes in without introduction, the letter will probably never be seen by a minister.
"Because I understand Whitehall, both from my present position as an MP and more particularly from my time in government, I can ensure that we are given a hearing. I can do that by using my own credibility with ministers to promote what WWS has to offer, thus ensuring that we meet officials at a level where decisions are made rather than papers simply filed."
In Monday's debate, Mr Nicholls had attacked the appointment of an independent commissioner, Sir Gordon Downey, to oversee MPs' ethics. "We got into this position ... because two stupid, silly, greedy Members did something that most of us would never do," he said, referring to Graham Riddick and David Tredinnick, who were willing to accept cash for questions from reporters posing as business men.
Yesterday Mr Nicholls said they "were taking cash for questions, from concerns they knew nothing about, for a product they knew nothing about. This [WWS] was a company well worth while promoting, from a West Country point of view".
Michael Heseltine, Deputy Prime Minister, took grateful refuge behind the new commissioner on BBC TV's Breakfast with Frost: "I have no detailed knowledge of this issue except what I have read in the papers, but there is now a parliamentary commissioner who can examine these matters.
Mr Nicholls's judgment has already cost him his ministerial career. He resigned from his post in 1990 after being found guilty of drinking and driving.Reuse content