Hello,
It is simply because the tour operator African Safari Club who is Swiss I think got rid of its Airline called African Safari airways using an A310-300. They operate from Switzerland, Austria, germany and the UK. Monarch has been doing the flight for them from LGW long before it ceased operations. It was freeing their airplane.
Man seems to be new and it is combined with Basel or Vienna because none of these places can fill a B767on a stand alone program.