The older British employees of the Permanent Assurance Company, a London firm which has been taken over by the Very Big Corporation of America, rebel against their corporate bosses after one of the men is fired. Having locked the surviving supervisors in the safe, and forced their boss to walk a makeshift plank out a window, they commandeer their office building, which suddenly weighs anchor, uses its scaffolding and tarps as sails, and is turned into a pirate ship. The office building starts to move as if it were a ship. Sailing through London, they proceed to attack The Very Big Corporation of America's skyscraper, using, among other things, filing cabinets which have been transformed into cannons and swords fashioned from the blades of a ceiling fan. On ropes, they swing into the board room and engage the executives of VBCA in hand-to-hand combat, vanquishing them.
After their victory, the clerks continue to "sail the wide accountant-sea", until unceremoniously meeting their end by falling off the edge of the world, due to their belief about the shape of the world being "disastrously wrong".
The Crimson Permanent Assurance suddenly re-emerges in the middle of the main feature of Monty Python's The Meaning of Life. The movies shifts to follow a modern board room debate about the meaning of life (and that people are not wearing enough hats). This debate is happening at the Very Big Corporation of America headquarters building in the same room that witnessed the battle in the short film. The talking ceases when one executive asks, "Has anyone noticed that building there before?" which turns out to be the London building/pirate ship of the Crimson Permanent Assurance. The audience gets to see the attack of the pirates from the angle of the victims in the board room. The raid is halted by a modern skyscraper falling out of the sky and onto the Permanent Assurance Company building; with a voice-over apologizing for the temporary interruption "due to an attack by the supporting feature.
I personally have seen this as one of Monty Pythons meanings of life and that some people work until the day they die. They work far too hard for far too long and at the end of the earth what do they have to show for it? Not much because they drive themselves crazy.