The issue of the shortwave service comes up pretty much every anniversary of this. From what has been written over the years, it was a fairly small issue compared to the Dutch service, Radio 819. At the time the Dutch were offering commercial radio licences if I remember rightly, some of which were for Medium wave and Radio 819 presented a threat to their success so it [Radio 819] had to be silenced.
Nobody was worried about Radio Caroline as they weren't either several years earlier with Euroseige.