The British establishment grasped onto the concept of citrus, and then did it really really wrong. First, they substituted cheap and easy to get limes - readily available from British holdings in the Caribbean - for the more effective lemons or oranges. Then they further boiled the limes in copper vessels, which had the non-helpful side effect of reducing the (thus far unknown) Vitamin C content even further.
People began to suspect that maaaaybe this whole citrus thing was not as effective as it had been claimed. Of course by then steam engines in ships brought the age of sail and voyages of longer than 6 weeks to an end. Semi-success-via-roundabout-ways!
Read more about how gradual advances gave us the real cure for scurvy at Atlas Obscura. Link