Re: "Where it already has taken us, surely?"
No, the next step beyond full intelligence take is criminal misuse of such database.
Only in faraway places like Prague & Sofia[0] have the police/lawful intercept/military intelligence collection groups/prime ministers recently been sanctioned for blatant misuse of their citizen-data-capture systems.
It's the next step that I'm worried about, as I currently trust Rt.Hon's DC & NC as average parliamentarians, the next step is to abuse the search function of your massive database and slightly make things worse for your targets/targetted groups/citizens. (France has admitted that they can keyword search an entire year of their citizens' internet history for a particular phrase or word)[1]
imagine a national blacklist - much bigger and nastier than the intelligence led Consulting Association Blacklist[2] - with someone nastier than dame Shirley Porter[3] in charge of the keywords and the subtle reverse-lottery prizes - this bad place is a place that UK is coming perilously near with the current NSA/GCHQ TIA fuckup[4]
but don't worry as Sir Malcolm, KCMG, QC will protect us?[5]
[0]http://www.novinite.com/articles/149591/Bulgarian+Prosecution+Hints+Spying+Breaches+Begun+with+GERB
[1]http://owni.fr/2011/08/31/amesys-amnesie-dpi-libye-kadhafi-surveillance/
[2]http://www.theguardian.com/business/2013/oct/12/police-blacklist-construction-workers-watchdog
[3]http://en.wikipedia.org/wiki/Homes_for_votes_scandal
[4]http://en.wikipedia.org/wiki/Information_Awareness_Office
[5]http://www.huffingtonpost.co.uk/2013/10/31/malcolm-rifkind-isc-snowden-guardian_n_4184238.html "Rifkind ...barely knows what day of the week it is"?