Britain blocks the Louisiana Purchase

What if Britain sabotaged the Louisiana Purchase, and how would that affect Napoleon's navy and French territory in North America?

Napoleon could seek funds from relatives ruling other states, while Britain had an interest in financing the sale and could instead try to intercept the payment.

British banks financed the American purchase, giving Britain an interest in allowing the transfer even though Napoleon received money. One proposed British tactic would be to extend credit to the Americans and then intercept the payment on its way to France. Napoleon could compensate for lost funds by demanding more from the relatives he had installed in charge of other states, so stopping the sale would not automatically stop his naval spending. A British invasion would more naturally come from Caribbean bases, because there was no practical northern infrastructure for the proposed advance from Canada. Britain might then sell much of Louisiana to the United States while keeping New Orleans to control the Mississippi, or establish a Bourbon government in exile there.