Elections

First elected to Parliament at the 1970 general election, where he defeated sitting MP James Dickens in Lewisham West, Gummer had previously contested Greenwich in 1964 and 1966. He was unseated in February 1974 by Labour's Christopher Price who achieved a 3.4% swing compared with a 1.3% swing to Labour nationally, deciding not to stand for the seat in the second election that year.

In 1979, he returned to the House of Commons, securing Eye in Suffolk, following the retirement of veteran Tory MP Harwood Harrison. He held the constituency and its successor Suffolk Coastal until his retirement from the Commons in 2010.

In government

Gummer was Parliamentary Private Secretary to the Minister of Agriculture in Edward Heath's government, before being appointed Conservative Party Vice-Chairman – a position he held until the government's fall in 1974. Following his return to the House in the 1979 election, he held various government posts and was Conservative Party Chairman from 1983 to 1985 – an office he held at the time of the Brighton hotel bombing during the 1984 Conservative Party conference. He joined the Cabinet in 1989 as Minister of Agriculture, Fisheries and Food, moving to become Secretary of State for the Environment under John Major in 1993.^[10]

As Environment Secretary he introduced the Environment Act 1995 and the Landfill Tax, which was the first such environmental tax in the UK. The BBC Wildlife magazine described Gummer as the "Environment Secretary against which all others are judged",^[11] placing him as one of its top ten environmental heroes. In 1997, he was also awarded the Royal Society for the Protection of Birds Medal,^[12] and was described by Friends of the Earth as "the best Environment Secretary we've ever had".^[13]

He had responsibility for food safety during the mad cow disease epidemic in 1989–90 which eventually claimed 178 British lives. At the height of the crisis in May 1990, he attempted to refute the growing evidence for BSE/Creutzfeldt–Jakob disease by offering his four-year-old daughter Cordelia a burger in front of press cameras, which she declined but he consumed during a Constituency event.^{[14][15][16][17]}

Gummer opposed the reduction of beds at the Aldeburgh Cottage Hospital in July 2005.^[18]

In opposition

Gummer managed to hold onto his seat in the 1997 Labour landslide victory, albeit with a much reduced majority of 3,254. He subsequently became a backbencher and chairman of the All-Party Group on Architecture and Planning. During this time he pursued environmental causes, introducing an Early Day Motion on global warming to Parliament along with Michael Meacher and Norman Baker.^[19] He was also instrumental in the passing of the Climate Change Act of 2008.

Because of his environmental credentials, in 2005 David Cameron asked Gummer to chair the Quality of Life Policy Group with Zac Goldsmith as his deputy.^[20]

In 2009, Gummer was involved in the United Kingdom parliamentary expenses scandal, after claiming £36,000 for gardening over four years, as a parliamentary expense. Although the claims were encouraged and initially approved by the Parliamentary Fees Office, rules state claims should only be made on expenses essential to parliamentary duties. He repaid £11,538 for gardening and household bills and donated £11,500 to charity, saying that he was paying above the minimum required in order to demonstrate "corporate social responsibility" for the expenses system. Subsequently, the Legg Report showed that 343 MPs had been asked to repay some money with Gummer paying the seventh highest figure.^[21][22]

House of Lords

It was announced that Gummer would be awarded a peerage in the 2010 Dissolution Honours List. On 21 June he was created a Life Peer as Baron Deben, of Winston in the County of Suffolk.^[23] He takes his title from the River Deben. He was introduced in the House of Lords the same day, supported by his brother, Lord Chadlington, and the composer Lord Lloyd-Webber.^[24]

As a pro-European moderate, Lord Deben supported Kenneth Clarke's leadership bids.^[25]

In September 2012, Lord Deben was confirmed as Chairman of the UK's independent Committee on Climate Change, succeeding Adair, Lord Turner. The committee advises the UK Government on setting and meeting carbon budgets and on preparing for the impacts of climate change. He is due to step down at the end of June 2023.^[26]