BP contrary to ignorant belief is not an oil company. It means Before the Present. I think it is calibrated to 1950 because of some problem related to Carbon 14 dating, possible after the nuclear age. Perhaps someone else can clarify that.
Well 1950 can hardly be construed as the present.
BP is an oil company which some think is British because it says British in the name, but it began as a German oil company that actually had no oil and that was named British for its London office.