Inverted Watermark King George V Three Half Pence

Hello )) Can't find any discussion about this, so, decided to create a new topic. I am reviewing stamps in glassine envelopes and found a few, which have inverted watermarks. Is it very common with these kind of stamps? First, I would like to share what I found about watermarks, and below - you will see the few stamps. I will apreciate all your comments and suggestions. Thank you.

Yes, quite common.

With GB stamps it was usual for booklet stamps, because of the printing process, to have half upright and half inverted watermarks. Of course, much more stamps were not from booklets so would normally have upright watermarks. Inverted usually but not always would mean a stamp from a booklet and a few of your illustrated stamps show cut edges (not torn) which is another indication of a booklet stamp. Some coil stamps would be with sideways watermarks depending on the delivery system... vertical delivery or sideways delivery of the stamps.
Your illustration of the watermarks as seen from the back of the stamp is a useful tool for someone not sure or beginning watermark detection.

Easy to find and a nice way to add to your collection. What more does a collector want.

Some pictures. The way you see them on the pictures indicates the positon of the watermark(more appealing than looking at the white backside of the stamp.)

Thank you!! ))