field officer
From Longman Dictionary of Contemporary Englishfield officerˈfield ˌofficer noun [countable] 1 British English someone who works for an organization whose job involves practical outdoor work, especially work connected with the countryside2 an officer of high rank in the British armyExamples from the Corpusfield officer• Since the field officer is a loner, he controls his output to a substantial degree.• The field officer, after all, has the power to make a discharger spend a substantial sum of money.