Harvey David Mathew Combe was born in 1943 in Adelaide, South Australia and was educated at Prince Alfred College and the University of Adelaide (B.A.). He became interested in politics at university and joined the ALP, partly through his friendship with Don Dunstan. (He has been Patron of the Don Dunstan Foundation since 2004.)
Combe was national secretary of the Australian Labor Party (1973–1981), a political consultant and lobbyist (1981–1985), an Australian senior trade commissioner (1985–1991), and has held senior executive and board positions within the Australian wine industry (1991–2008).
After completing an arts degree at the University of Adelaide, Combe became active in Labor Party affairs in South Australia. He moved to Canberra and in 1973 became the youngest serving National Secretary of the Australian Labor Party after the election of the first Labor government for 23 years. In November 1975, he was allegedly co-instigator, with Gough Whitlam and Bill Hartley, of an (unsuccessful) approach to Saddam Hussein's Iraq for a $US500,000 gift to help fund Labor's 1975 election campaign. Labor lost the 1975 election. He propagated the notion that Labor's defeat in the election had been contributed to by CIA interference, and wrote an article on the subject which appeared in The Bulletin in January 1982.
Combe remained National Secretary until July 1981, at which time he resigned to establish his own lobbying business, David Combe and Associates Pty Ltd. The business reportedly "received a great fillip in March 1983, when the Labor Party was re-elected to office. Business perceived Combe as the most influential lobbyist then working in Canberra".
In 1983, he was accused of compromising Australia's national security in dealings with Soviet diplomat Valery Ivanov.
The Combe-Ivanov affair developed out of a trip Combe and his wife made to the USSR in 1982, in the course of preparations for which they met and developed a relationship with the First Secretary for the USSR Embassy in Canberra, Valery Ivanov. Soon after the formation of the Hawke government, ASIO raised concerns that Combe, closely aligned to the ALP, might be being compromised by a Soviet citizen with KGB links. Ivanov was expelled from Australia in 1983 by Prime Minister Bob Hawke.
The highly publicised events were investigated by the Hope Royal Commission into Australia's security and intelligence agencies of 1983–1984, which found that Combe had indeed been targeted by the Soviets. Although targeted, there was no proof of intelligence breaches, nor security threats to the country. There were several cartoons that portray the commission as a kangaroo court.
He was Australia's senior trade commissioner in Western Canada from 1985 to 1989, and in Hong Kong from 1990 to 1991.
Combe is credited with developing significant export business for Southcorp Wines from August 1991 to June 2000, during which time exports increased from $40 million annually to $300 million. Combe was Senior Vice-President International and ran the European operations of Penfolds and Southcorp Wines during the rise of Australian Wines in the 1990s.
In the year 2000. he was named "Australia's Top Export Salesmen" by Overseas Trading magazine and was included in the "Twenty Five Most Influential Australians in Asia" list published by Business Asia magazine, 2000.
From March 2001 to November 2003, he joined Western Australian wine producer Evans and Tate Limited as a non-executive director with a view to providing strategic input and guidance in an ambitious acquisition programme.
In 2004, in a speech at Bordeaux, he lambasted the wine-purchasing policies of UK supermarkets which "if committed in Australia, would represent major breaches of the trade practices laws".
In June 2004 he was appointed chairman of Simon Gilbert Wines, He retired as a director and chairman in February 2007, "to take up another position within the wine industry".
In 1983, Keith Looby painted Combe's portrait. The portrait was an unsuccessful entry in the Archibald Prize of 1983, and conspiracy theories on this matter abound. David Combe said in 1998 that there was 'circumstantially a good case to believe that some trustees were heavied by the Party' into rejecting the work. In 1998, Combe donated his portrait to the collection of the National Portrait Gallery in Canberra, "through the Australian Government's Cultural Gifts Program".