Buster the Bear is right........ BAF did have a 146 for the Route Proving ( 200 Hrs ? ) part of certification. I should know as I was one of the Engineers flying with it.
IIRC we had Flt crew from BAe and BAF with cabin crew from BAF. Based at Southend the aircraft was used to simulate airline operations ......a typical flight was Southend to a BAe base ( Hatfield, Filton, Warton , Brough ) fill up with employees and fly to Jersey or Bauvais or Munich and then return. Interesting times .......especially the full evac due smoke in the cabin, and plenty of starter motor changes.