Adam Werritty, the self-styled adviser to Liam Fox before his resignation from Cabinet, has broken his silence to admit he was "naive" and "knows very little about defence policy".
Dr Fox quit as defence secretary when it emerged his close friend used business cards claiming to be an official Ministry of Defence adviser and had accompanied him on a significant number of foreign trips.
In an article written for Spectator magazine , Mr Werritty acknowledged he made mistakes and said he is now "planning a future well away from politics".
"Much of what was written and reported was long on drama and innuendo, but short on details and specifics," he said of the media storm earlier this year.
"What had this 'villainous' Adam Werritty actually done?
"I know and accept that I made mistakes, some of which were sufficiently serious to have played their part in Liam's resignation as defence secretary. As a close friend of his, I found this particularly hard.
"I was certainly naive not to have better considered how my role, and regular contact with Liam, would look from the outside," he added.
He said he is still friends with the Conservative MP and plans to spend Hogmanay with Dr Fox and his wife Jesme Baird.
"There are some things that even storms in a Sri Lankan teacup don't change," he explained.
Mr Werritty says he worked with Dr Fox to support his efforts to secure reconciliation in Sri Lanka and helped remove long-standing emergency regulations there.
He claims that far from posing as an MoD adviser, he never meant to suggest he was an expert in defence.
"I've been asked on several occasions why I didn't apply to be a special adviser," he wrote.
"The answer: I actually know very little about defence policy and have never pretended otherwise. Why should I be paid by the taxpayer for an expertise I didn't possess?
"So I continued to work outside of 'officialdom' in what was certainly an unusual role. I was funded by a number of donors and my job was to research and network. To meet various experts, attend forums and conferences and get a solid understanding of various foreign affairs issues."
Mr Werritty, best man at Dr Fox's wedding, said he regretted setting up a coffee meeting between the-then defence secretary and businessman Harvey Boulter in Dubai.
It was this unofficial meeting that helped unravel Dr Fox's ministerial career.
A report by Cabinet Secretary Sir Gus O'Donnell found the Conservative politician's friendship with Mr Werritty broke the ministerial code and allowed a potential conflict of interest to arise.
The Spectator says Mr Werritty asked that his fee for the article be donated to the charity Help For Heroes.