Peter Collecott was born 8 October 1950, the son of George William Collecott and Nancie Alice Collecott (née Salmon). He was educated at Chigwell School, Essex and St John’s College, University of Cambridge (MA 1976; PhD 1976), then was Kennedy Scholar at MIT, 1972. In 1982 he married Judith Patricia Pead.

After a year as a Royal Society Fellow at the Max Planck Institute for Physics and Astrophysics, Munich, 1976–77, Collecott joined the Diplomatic Service in 1977 and his diplomatic career included: Foreign and Commonwealth Office, Southern European Department, 1977–78; MECAS, Lebanon, later London, 1978–80; 1st Secretary: (Political), Khartoum [Sudan], 1980–82; 1st Secretary (Economic, Commercial, Agriculture), Canberra [Australia], 1982–86; Head, Iran/Iraq Section, Middle East Department, FCO, 1986–88; Assistant Head, EC Department (External), FCO, 1988–89; Counsellor, Head of Chancery and Consul General, later Deputy Head of Mission, Jakarta [Indonesia], 1989–93; Counsellor (EU and Economic), Bonn [Germany], 1994–98; Head, Administrative Restructuring Review Team, FCO, 1998–99; Director, Resources, FCO, 1999–2001; Deputy Under-Secretary of State and Chief Clerk, subsequently Director General, Corporate Affairs, FCO, 2001–03; Ambassador to Brazil, 2004–08.

Following his retirement from the FCO, Collecott served as Special Adviser to International Sustainability Unit, Prince of Wales’ Charities, 2010–15 and Diplomatic Adviser to Goverment of Catalonia, 2013–16.