Treaty-exempt sloops could have transformed the Battle of the Atlantic

Could Britain have produced its Second World War escort ships earlier?

Yes; treaty-exempt sloops could have been mass-produced throughout the 1930s and might have given the Royal Navy about 200 additional escorts by 1939.

Interwar treaty language allowed unlimited sloops below specified displacement, speed, and armament thresholds. The Royal Navy therefore could have ordered one escort sloop alongside each destroyer without consuming its treaty-limited destroyer tonnage. Repeating that policy through the 1930s might produce nearly 200 modern sloops by 1939, plus older destroyers and new destroyer classes. Emergency escort building would still continue, but it would reinforce an already overwhelming anti-submarine force rather than repair an acute shortage.