Royal Navy convoy exercises used fleet auxiliaries

Did the interwar Royal Navy omit dedicated ASW exercises for defending merchant convoys?

No: it used Royal Fleet Auxiliary ships as simulated merchant convoys and trained escort and hunting groups, though the armed stand-ins created unrealistic assumptions.

The interwar Royal Navy did run dedicated convoy-ASW exercises. Instead of paying merchant operators to remove ships from trade, it used Royal Fleet Auxiliary tankers as stand-ins for merchant columns. Escort and hunting groups could therefore practise convoy protection without the commercial expense of chartering civilian vessels. The substitution was economical and produced useful doctrine, but armed auxiliaries taught submariners different risk calculations from those posed by unarmed wartime merchantmen. The exercises were real, and the choice of simulated convoy helped create one of their blind spots.