the.com/double cream

means A high-fat cream (roughly 48% butterfat) thick enough to spoon or softly whip without any effort, standard in British kitchens for pouring over puddings or dolloping onto scones.

from Straightforward British dairy naming rather than hidden wordplay: 'double' marks it as roughly twice the fat content of ordinary single cream, the two having been sold and labeled side by side in Britain since cream grading became standard practice. No myth to debunk here — just the plain arithmetic of butterfat percentages dressed up as a product name.