More info required
Did this near miss happen in "E" airspace? The Virgin 737 on a normal descent profile would transit the "E" airspace such that it would be at F180 around 55dme and back into "C" airspace at 40dme and F130. Surely at these levels the aircraft involved (the "Cessna twin") must have been IFR??
On the face of it, this incident would seem unlikely to be the "IFR Vs VFR conflict in E airspace" scenario we are all dreading. It will be interesting to hear the actual account.