Identifying Plate Numbers:
Plate numbers for Penny Red's for Cyprus stamps can be identified as indicated on each side of the stamp.
However, they are not very easily distinguished unless you have a good jewellers loop (with light) or a decent magnifying glass.
The plate number is generally written bottom to top on the left side of the stamp and within the pattern of the stamp edging – and on the right side, it’s written in the opposite direction – top to bottom.
See the example shown below with Plate 217 (SG 2) 1880 Penny Red
Another example here by Stanley Gibbons (not Cyprus)
Information Page Links below:
History of Cyprus stamps
Plate Numbers on Cyprus stamps
Understanding Philatelic Terms & Descriptions