How much fuel did Britain store before the Second World War, and how did other nations react when they learned of it?
Short answerA very large amount accumulated through sustained interwar purchasing; no tonnage or reaction from another country is specified.
NotesBritain's fuel-oil stocks are described as exceptionally large, without a precise quantity. The Royal Navy repeatedly bought and stored oil through the 1920s and 1930s. The image of floating Great Britain on the accumulated fuel is an exaggeration used to convey the scale of the reserve. The question also asks how other countries reacted, but the brief reply does not identify a foreign reaction.