Just a thought...General Macready was the commander in Chief, Ireland at the time. If you go to The National Archives website and search their records using 'General Macready' as the search term and using 1921 as the year, the result includes a long list of weekly reports submitted by Macready - maybe it is one of these referred to in the Westminster archives. The reports and files containing correspondence between Macready and Greenwood form part of the Parliamentary archives not digitised so they would need to be viewed in person.
