 After a period working as the "FT"s Wall Street correspondent she joined "The Guardian" in May 1999, remaining in New York as the US business editor.She became the news editor for the City coverage of "The Guardian" when she returned to London in 2002, and then media business editor in January 2004.Martinson was appointed as "The Guardian"s media editor in 2007, and assumed the post in January 2008 after returning from maternity leave.