Old UK military film about Belize incredibly smug and insulting

Whoever scripted this hated Belize almost as much as they hated Britain — it's so sanctimonious, condescending, self-loathingly offensive you suspect it's dark comedy and start looking for Peter Serafinowicz to show up. But it's an old explainer for upper-crust military officers, apparently, a glove that certainly fits all the above. It's gone viral as an artifact of the 1980s, but by then Belize was independent, so it's probably older. The political backdrop: Belize was supposed to become independent in the 1960s, but Britain knew Guatemala would invade if they left, so things got very complicated. It's one of the funny little secrets of decolonization that Britain was responsible for Belize's defense well into the 1990s and never really left.