The Office for Communication (Ofcom) is the organisation that regulates the radio spectrum in the UK.
Ofcom lay down the rules (Licence Conditions) for ALL users of the radio spectrum including the BBC and ITV, Mobile Phone Companies and Amateur Radio
Ofcom issues amateur radio licences and callsigns in the UK
The Radio Society of Great Britain (RSGB) is the organisation that represents radio amateurs in the UK.
The RSGB also looks after the day-to-day administration of radio amateur exams in the UK.