What would one hundred reserve sloops change in 1939?

What might change if the Royal Navy entered World War II with roughly one hundred reserve sloops?

More patrol and escort hulls could make Scapa Flow harder to penetrate, protect carriers and convoys, and damage the U-boat arm earlier.

The scenario assumes Britain had built roughly twelve sloops per year from 1930 and could mobilize about one hundred by 1939. Extra patrols around Scapa Flow might deter or defeat the penetration that sank Royal Oak, while additional escorts could better protect Courageous and Atlantic convoys. Earlier U-boat losses would remove experienced commanders who were learning together and would otherwise shape later operations. The counterfactual illustrates how inexpensive reserve escorts can protect capital ships and alter an enemy force's development before new wartime construction arrives.