Ah right Chris. I see now.
It was more useful in the days of film photography and before digital imaging software became popular.
The polarising lens was used for effectively reducing reflections, bringing out clouds and deepening blue skies by rotating the filter in use. The camera had to be held at a certain angle from the sun to get the best effect.
This can still be done using a digital SLR with the same effect, but people tend to just prefer to use the features and convenience of Photoshop or Light Room I think, for the same effect.
I was going to send you one on to try but after rummaging through my photo drawer, I found that have the 58mm, 72mm and 77mm but sadly no 62mm, which is the filter thread size for the Tamron.
If you have another lens you wish to try it on, let me know.
Tony