[2][3] After rising through the county branch, in 1965, Plumb was elected vice-president of the National Farmers' Union.

[7] Plumb's term of office included British accession to the European Economic Community and its Common Agricultural Policy and Plumb negotiated for greater support for British agriculture; he stressed that Britain no longer had the economic power to bring cheap food prices.

During the papal visit to the European Parliament in Strasbourg, Pope John Paul II was delivering a speech.

Northern Ireland MEP Ian Paisley, a staunch Protestant and opponent of Catholicism, heckled throughout the delivery, brandishing posters accusing the Pope of being the Antichrist.

[3] In June 2012, the Bureau of Investigative Journalism and The Independent newspaper revealed how senior members of the House of Lords failed to disclose their business interests in a public inquiry.

As of July 2012, Plumb's entry in the register of interests listed his only remunerated employment/profession as 'farming',[18] despite his involvement with the Brussels-based lobbying firm Alber & Geiger since 2007.