Thanks for those pics Propliner. I guess they were diversions from Leeds where the n/b and s/b NWI>LBA>EDi>ABZ (and v.v.) services both morning and evening were scheduled close together and often met on the ground.
The Dak was still used on one rotation a week, including the Sunday eve n/b, probably AQ204, until 1974. Presumably this allowed the a/c to rotate back to NWI for maintenance.