Took me three 'collections' before I 'found' the GB LE period and its
complexities.

Good hunting!

Excuse my ignorance. What does LE stands for?

"Line Engraved" One of the three major methods for producing stamps.
In particular, they concern the Penny Blacks, Reds, Tuppenny Blues and
the 1/2d and 1 1/2 d produced by Perkins Bacon up to 1870.