OK, I have the Half Annas sorted, good to get this out of the way.
Exists 3 varieties, 1855 Unwatermarked (easy)
1865 Wmk 38 (Die l only) Exist Blue and Pale Blue.
1873 Wmk 38 Die ll
All typographed by DelaRue.
Die l v Die ll you ask?
I failed to get Gibbons suggestion, fortunately Her Majesty's eye, seem to rarely get cancelling ink.
So Die I will have 3 straightish lines under her Eye
Die ll appears to me to be an "h" or an "m" (sideways) under her eye
In my collection so far, I have 1 x Unwmk, 5 x Die 1, 5 x Die ll
Die I all appear to be "Pale Blue"
Wmk and ID images : Stanley Gibbons Brit Comm 1972
The Unwmk has a strange Postmark for me.
1865 Die l
1873 Die ll