Ahh the easy acceptance of change by pilots!
Who would have thought it!
Having a think about the possible options, there isn't an awful lot of potential choices that were relevant to the brand.
The other choice was something with no connection to the brand, along the same lines as virgin America - redwood.
Somehow I don't think that pprune as a callsign got a run!
Though "Centre pprune 456 climbing to FL360" does have a ring to it!