All 30p  has one of the following characteristics:
Subtype 1 (22 on a sheet) : Point in front of F, thick P (top)
Subtype 2: (16 on a sheet): Coloured dot in pothorns loop
Subtype 3 (2 in a sheet) ...

Here are all the positions from a sheet - two first rows are upside down, middle row is 90 degrees, all here shown straight

1:1  Subtype 2	1:2  Subtype 2	1:3  Subtype 2	1:4 Open P  damaged 3	1:5  Subtype 1	1:6  Subtype 1	1:7  Subtype 2	1:8  Subtype 1
2: 1	2:2	2:3  Subtype 1	2:4 Lower 3 damaged	2:5 Subtype 1	2:6  Subtype 1	2:7	2:8  Subtype 2 Strange lower 3
3:1  Subtype 2 cut A  cut 0	3:2  Subtype 1	3:3  Subtype 2	3:4 cut A	3:5  Subtype 1	3:6  Subtype 1	3:7  Subtype 1	3:8 Damaged O
4:1  Subtype 1 Open mouthpiece	4:2  Subtype 2	4:3  Subtype 1 R-ball	4:4  Subtype 2 Open frame left, faint R-ball	4:5  Subtype 1	4:6  Subtype 2	4:7  Subtype 1	4:8
5:1  Subtype 1	5:2  Subtype 2 Scrisorfi	5:3	5:4  Subtype 1	5:5  Subtype 1	5:6  Subtype 1	5:7	5:8  Subtype 2

all images courtesy of Harmers of London
Roberto Sciaky collection