In his letter of resignation, Fox apologized for errors in judgment, The Daily Telegraph reported. He said he was proud of his part in the overthrow of Libyan strongman Moammar Gadhafi and of his efforts to reform the Ministry of Defense and the British military.
"As you know, I have always placed a great deal of importance on accountability and responsibility," he said. "As I said in the House of Commons on Monday, I mistakenly allowed the distinction between my personal interest and my government activities to become blurred."
Adam Werrity, who shared an apartment with Fox before his marriage and was best man at his wedding, made at least 18 trips abroad with Fox. Werrity had no official government position but handed out business cards that described himself as a Fox "adviser."
Fox, a native of Scotland, studied medicine in Glasgow and practiced as a doctor until his election to Parliament from an English constituency in 1992. He rose quickly through the Conservative ranks and has been especially popular with the party's right wing.
"I'm very sad to see him go," Patrick Mercer, a member of Parliament, told Sky News. "This was a trial by media."