Pretty sure he should have said 24 escorts (ie frigates and destroyers) - there has been talk of an aspiration to increase from the current 19 to 24, by means of the Type32. But having all 24 in service by the end of the decade (as opposed to in service or in build) sounds an unfeasible stretch. If the true situation is an expansion to 24 escorts overall by the early 2030s that wouldn't be such a bad outcome.