Received the below email from Kevin McMullin 14/09/09 which clears this one up ..many thanks
This is all one aircraft - G-USTA. As you've said, It was used by Castle Air charters, a prolific supplier of aircraft [usually Augusta 109s] to the TV and Film industry as camera ships and "star aircraft".
The aircraft was used in "Interceptor" (The follow up programme to "Treasure Hunt") as G-MEAN, Re-Registered as G-USTA, Sold off, Crashed by the new owners, and bought back by Castle as spares.
Fast forward to 2006, and one of Castle Air's other A109s, G-BVCJ is used in the hit BBC TV show "Casualty" as an air ambulance, using star of life and appropriate markings over her usual blue and white paintwork. Part of the program shows said aircraft crashing. Remind me never to visit Holby, it's a dangerous place!
Now the clever bit. Rather than destroy millions of pounds worth of aircraft by crashing a decent helicopter, Castle air simply re paint the bits of G-USTA that the camera will see to look like G-BVCJ, so the port side is not painted. Add a few Special effects shots (very easy!) to make it appear that something very nasty has happened to G-BVCJ, and put the already damaged fuselage of G-USTA into the apporpirate positioning. Then don't show the black bits.
Post filming, no point in re-painting a wrecked aircraft just to have it sit around.
Then Vertiair buys it, and it's now the flight simulator.
This is using info from interceptor's lair, a forum of fans of the aforementioned TV gameshow with links to Castle Air.