yes, as blocks of phone numbers have to be licensed from ofcom and it costs the telephone company money – the only time a phone company will change your number for free is if you are getting harrased and you have a report from the Police saying this…

if you are really paranoid then in most towns there are random foreign dudes selling SIM cards, buy one of these and a cheap mobile and use this for anything “sensitive”.

tracking individuals is expensive though, and unless you are selling its not worth the feds bothering especially when the usual penalty for possession of anything is just a Formal Caution..