L's decimal questions!

I went wandering around on the forum to try to work out which thread was best to add my question to, however, I quickly realised that, not only will this be resuscitating some very old threads, but, it will also mean that I will have to check several threads to look for replies, so, I hope members don't mind, but, I'll amalgamate them here. (If this is an issue, if a mod will let me know I'll delete this and go back to the alternate way).

For my first question, I have this:



I'm using the Seven Seas catalogue and it doesn't mention this stamp, although, I noted that it does exist in 'Perfs14''s awesome collection photos, as seen here:
thestampforum.boards.net/attachment/download/1166

Can anyone please let me know what year these were done and whether they have any value?

All the examples I have are used, some very lightly postmarked and some medium.

Thanks

L.