When BA or Virgin or Easyjet buy a new type of plane, it isnt sent to QinetiQ at Boscombe Down for testing. Boeing or EADS do all that.
No. The manufacturers do their own testing, but then the relevant national Authority (FAA in the US, JAA/EASA in Europe, etc) does its own independent Certification testing before paying passengers get a look in.
Slightly off thread, but just putting things straight.