1922 Dollard 5-line Overprint in black "PROOF"

1922 Dollard 5-line Overprint in black, proof on thin, wove paper without backstamps, block of 20 from the junction of 4 stereoes from within setting 2a. The block shows several examples of the setting variety "R over Se", and exhibits a clear misalignment between the two middle vertical rows as well as a slight "raised c" in Sealadac on position 14. Ex Gerard Brady. Hib. PR2.
Despite some creasing, a rare and spectacular Exhibition piece.
The make up of this block in terms of clichée positions within the stereo is as follows:
Row 1: 8, 9, 7, 8; Row 2: 11, 12, 10, 11; Row 3: 14, 15, 13, 14; Row 4: 2, 3, 1, 2; and Row 5: 5, 6, 4, 5.