All this debate about aerodrome licenses is interesting but, I suggest, irrelevant as far as controlling (in the broadest sense) is concerned.
Within EU States (under ESORR 5, I think) it is mandatory to have an ICAO approved License to provide an ATC Service, including FIS. In the UK, there are currently some exceptions (e.g. UK Military Controllers who have their own licensing scheme) but the CAA has decreed that all must comply by a deadline later this year.