Carter joined the firm J Walter Thompson (JWT) in 1986[2] as a graduate trainee,[2][3] specializing in media and technology.[11] In 1994 JWT named him managing director[3] and CEO of J Walter Thompson Company UK & Ireland.[2][3] He then became JWT's managing director in 1995 and chief executive in 1997.[13]
In 2000 Carter was appointed the chief operating officer and managing director of UK cable TV company NTL UK & Ireland[3] (now Virgin Media).[4] The company was deeply in debt, and Carter helped oversee complete restructuring of the UK & Ireland business.[3] Given debts of £12 billion[14] and market conditions, the company was required to file for Chapter 11 bankruptcy protection,[3] with Carter presiding over the bankruptcy proceedings.[14] The company was still in Chapter 11[15] when he left in 2003.[6] His compensation payoff, rumored to be close to £1.5 million[3] with a £600,000 bonus,[15] met with criticism from shareholders,[3] and in late 2007 the company resolved a class action lawsuit brought by shareholders by paying out $9 million in compensation.[15]
Ofcom and Brunswick
On 1 March 2003[13] Carter became the founding CEO of Ofcom (Office of Communications),[1][3][5] the British government's new media regulator. Among other issues, Carter focused on regulating broadband prices and coordinating regulation of switching from analog to digital television broadcasting.[3] He also led negotiations with BT on matters such as local loop bundling.[16] Stepping down from Ofcom in the summer of 2006, he was a part of the capability review team in 2006 and 2007 that reviewed the Department for International Development.[7]
Carter entirely vacated his brief political life, and not voted or spoken in the House of Lords since December 2009.[24][25]
Alcatel
In April 2010[26] Carter joined the French-American company Alcatel-Lucent, becoming director of marketing, strategy and communications and relocating from London to Paris.[16] This was a private profit role that benefitted from his previous regulatory and ministerial roles. His official titles as of 2010 were executive vice president and chief strategy & marketing officer.[12] Beyond serving as a managing director,[27] he became the company's president of operations in Europe, the Middle East and Africa. He returned to London and officially retired from Alcatel-Lucent in April 2013, although he continued to work on special projects for the company through that summer.[9]
Informa
Carter was appointed a director of the board of Informa,[27] an information services group,[10] in 2010.[27] In 2013, the Informa board unanimously voted to appoint him as CEO, succeeding Peter Rigby, in July 2013[27] - a role he assumed in early 2014.[28] As CEO of the company he maintained the focus on investing in subscriptions, bookings and sponsorship, as well as expanding in international conferences[4] such as the Monaco Yacht Show.[28] Under Carter, in 2016 the company acquired the American events company Penton for £1.2 billion.[4] In January 2018, Informa announced the proposed acquisition of UBM, an events group, for £3.9 billion.[29] Carter, who became chief executive of the combined group, said at that point that he would retain the other parts of Informa, including business intelligence and its academic publishing business Taylor & Francis.[30]