See the lower left stamp in the large block of 12.
Stamp 20 - row 4 column 2 is not included because of insufficient evidence at this time.
See lower right stamp in the large block of 12 and the top left stamp in the lower marginal Dubois block.
Hence this stamp links the two blocks together.
See the top right stamp in the lower marginal Dubois block.
Stamp 23 - row 4 column 5 is not included because of insufficient evidence at this time.
This plating classification is an educated guess based on elimination.
On the other evidence, this right marginal stamp cannot be from rows 1 to 3.
If from row 5, the lower selvedge might also have been left intact (?)
Use the links below to go to plating in the following sources:
Overview of 2½d (2/6) plating.