I believe that most of the civil certification was done by Transmeridian/British Cargo Airlines using Mashall's of Cambridge as the design authority. Both PS & PE flew with a Marshalls class 'B' registration during testing.
It had originally been the intention to paint PE in the black and blue colours planned for British Cargo Airlines, the paint was even in the hangar at SEN waiting to be applied. In the end both PS & PE recieved the Transmeridian colour scheme and titles, later modified into the Heaveylift livery.