WMU's policy was for all UK instructors to have a FAA ATP & CFI as a minimum and would not allow any instructing to be done on the cadets until so qualified. Personally I cannot understand anyone wanting to do it any other way, very unprofessional.
The FAA did indeed stop it happening at other schools, mainly in Florida. I had a discussion with an FAA examiner (FAA employed) and he was very pleased to see WMU leading the way...