So it doesn't!!!
Many thanks.
What I did find odd was that when searching for the Lux app via the Play Store app on the S3 Mini nothing came up, however when I searched again using the Play Store app on my S3 for the Lux app Play Store displayed it.
Are we to assume then that if, like the S3 Mini, your phone doesn't have certain functions such as an auto-brightness function the Play Store app "knows" this and won't display any apps that involve the use of the auto-brightness function?