I've seen some trifolds with British flag decals and even CHPT3 paint schemes, but AFAIK none branded Brompton or using Brompton's font (both trademarked).

There are any number of unauthorized t-shirts available on the internet bearing Brompton logos and graphics. Apparently, Brompton allows that for the advertising value they get from it (?).




Brompton did have that well-documented trouble with jackleg subcontractor Neobike back in the 1990s. IIRC even Neobike's owners' manual was a photocopy of the Brompton owners' manual!



Fun fact: As Andrew Ritchie started negotiations with Eurotai to build Neobike-Bromptons in Taiwan, Dr. Hon called him up and said, "You don't want to do business with those guys." In a decision that would haunt Brompton for over a decade, that advice was dismissed.