yeh, could easily have been "cleared to cardiff". That is where the aircraft is going, regardless of where it starts
My guess on the flightplan is that they have filed a route to the area, and back again, with a /rmk in field 18, where they write the flights purpose, and that a requested holding at this area are most lilkey.
Perhaps they plotted in a kind of a "cirle" in the area that they can fly along, using long/lat positions..?