The True Brit 25 is reverse engineered from a G12M.
It differs from the Chinese made Celestion G12M in that the motor unit is machined an plated in the UK, and the soft parts (spider, cone etc) are UK made by Kurt Muller, who as I am sure you are all aware where one of the original suppliers of parts to Celestion.
Tayden also wind their own voice coils.
We are having our web-site updated (by a drummer!!) and this will include some sound samples of the True Brit 25.
From my experience with these speakers they do benefit from breaking in.