Neutered, a sartorial generic applicable to standard trench redesign. Keach's knockoff fits that bill.
A nice look trench, but I honestly do not understand why the original trench had to be altered.
Trench coats are an idea not a dogma - I don't think fashion or most garment makers care about the intricacies or heritage of garments they make. Pretty sure this '80's TV production didn't care either.