Gregory graduated in History, Economic History & Politics from London University in 1987 and has over ten years experience of working in the City of London. In 1988 after working at the Centre for Policy Studies with David Willetts, Gregory trained as smaller companies analyst and subsequently became a Corporate Finance Director of the Australian owned International Pacific Securities, specializing in cross-border mergers and acquisitions.
In 1997 Gregory became an Associate Partner of the leading financial public relations firm, Brunswick Group Ltd. The following year he was appointed head of International Investor Relations for Sibneft, a major Russian oil company, where he helped lead the company's drive to modernize in the post Soviet economy and open up to Western markets. He returned to Britain in May 2000, to continue as a director of Bartlett Scott Edgar, the recruitment advertising business, of which he helped lead a "management buy-in" in 1998. The company was sold to TMP Worldwide in 2001.
Gregory was elected Conservative Member of Parliament for Bexhill and Battle in his native Sussex in June 2001.
Gregory served on the House of Commons Environmental Audit select committee between 2001 and 2005. He was appointed to the Opposition Front Bench as a Conservative whip in 2003, resigned on July 2005 to help run David Cameron's successful leadership campaign.
David Cameron appointed him Shadow Minister for Climate Change & Environment in December, 2005. Greg accompanied David to the Arctic in March 2006, to highlight the dangers of global warming and has since been working closely on Climate Change and wider environmental policy, his policy paper "Power to the People" advocating a radical increase in the use of decentralised energy, greatly informed the Conservative Party policy paper of the same name, published in November 2007.
Greg led the passage of the Climate Change Bill through the House of Commons in 2008 and was a key author of the Conservative Party’s ‘Low Carbon Economy’ green paper, launched in January 2009.
In October 2008 he was promoted to Shadow Climate Change minister in the new Shadow Department of Energy and Climate Change.