LONDON — Britain's defense minister Liam Fox quit his post Friday after days of allegations about the influence-peddling of a close personal friend who joined key visits overseas and posed as an unofficial aide.
Fox acknowledged he had blurred the lines of his professional and private lives in allowing Adam Werritty, who had previously worked as a defense lobbyist, to organize meetings and join him during 18 trips overseas.
A government inquiry into the case will continue to investigate whether Werritty used his access and friendship with Fox for personal gain, or on behalf of others seeking to win favor or contracts with Britain.
Prime Minister David Cameron named Philip Hammond, who had been Transport Secretary, as Fox's replacement – asking him to take on the task of implementing severe defense cuts under a national austerity program and to negotiate the exit from the violent conflict in Afghanistan by the end of 2014.
Fox wrote that he was leaving his role "with great sadness" in a resignation letter, but appeared to have little alternative after more than a week of scrutiny of his personal ties to Werritty.
"I mistakenly allowed the distinction between my personal interest and my government activities to become blurred," Fox told Prime Minister David Cameron in the letter.
Though he had no official or paid role with Britain's government, Werritty – who was Fox's best man at his 2005 wedding and previously lived at Fox's apartment – met with the minister at least 40 times since he took office, and had distributed business cards claiming to act as his aide.
Fox became the first Conservative Party lawmaker to resign from Britain's Cabinet since the country's coalition government was formed following an inconclusive election in May 2010.
However, Cameron's inner circle are also awaiting the outcome of an investigation into another Cabinet heavyweight – with prosecutors reviewing allegations that Energy and Climate Change Secretary Chris Huhne attempted to dodge a speeding ticket to avoid a driving ban, a case that could further disrupt Britain's government.
Cameron had initially said he would await the outcome of a government report into Fox's friendship with Werritty before deciding on the minister's fate – seeking to appear fair to a one-time challenger for the leadership of their Conservative Party.
Fox had pushed through work on an 8 percent cut to the defense ministry's annual 37 billion pound ($59 billion) defense budget, deciding that 17,000 troops, a fleet of jets and an aging aircraft carrier would all be lost.
He had ensured Britain's armed forces would be "fully equipped to meet the challenges of the modern era," Cameron said, in a letter to Fox.
"On Libya, you played a key role in the campaign to stop people being massacred by the Gadhafi regime and instead win their freedom," Cameron wrote.
Werritty, in his early 30s, has been interviewed by the government inquiry, but is yet to offer any public comment about his role or how he funded his hectic travel schedule following Fox across the globe.
Details released by Britain's defense ministry show Werritty joined Fox on visits to destinations including Washington, Bahrain, Hong Kong, Sri Lanka, Israel and on frequent travel to Dubai.
Werritty was present at a steakhouse dinner in Tampa, Florida, with Fox and Lt. Gen. John R. Allen – now the top U.S. commander in Afghanistan – and also joined family holidays with Fox in Spain and Switzerland.
The furor also saw Fox's colleagues forced to discuss repeated insinuations that he is gay.
Though Fox married his long-term girlfriend Dr. Jesme Baird in 2005, opponents raised similar questions about his relationship with Werritty after the extent of their contacts was revealed.
The younger man had previously worked for Fox's Atlantic Bridge organization, a now-defunct charity which promoted his hawkish foreign policy views and sought to become a forum for neo-conservatives in London and Washington.
Fox, who contended for the Conservative Party leadership but came in third in a contest won by Cameron in 2005, was closely allied to Margaret Thatcher – who was patron of his charity. The ex-Prime Minister attended his 50th birthday party last month, even though she is now aged 86 and usually too weak to go out in public.
The departed defense minister was known in academic and policy circles as an Atlanticist who favored closer ties to the United States, was deeply skeptical about European allies and had alienated some parts of the party with his views.
Fox had clashed with other ministers over his links to Sri Lanka's government.
Main opposition Labour Party lawmaker Jim Murphy said that Fox's actions in allowing Werritty access to visits, and to arrange a meeting in Dubai with a potential supplier had breached rules governing the conduct of ministers.
"This issue has centered solely on his judgment and his conduct in one of the most serious jobs in the country," Murphy said.
Supporter Louise Mensch, a Conservative Party legislator, said Fox's exit was regrettable. "He was an outstanding Secretary of State for defense and a completely dedicated minister," she wrote on Twitter.
Analysts urged Hammond to quickly master his brief, with U.K. forces still in action in both Libya and Afghanistan.
"It's a morale issue, it's an uncertainty issue," said Guy Anderson, chief defense industry analyst at IHS Jane's. "At times of war, this can't be good."
Cameron's office said Hammond would be replaced at the transport ministry by Justine Greening, a rising 42-year-old legislator within Cameron's party who had been a junior minister in the Treasury. Greening will herself be replaced by another young female rising star, 29-year-old Chloe Smith, who takes over Greening's role as economic secretary.
Meera Selva and Cassandra Vinograd in London contributed to this report