If you think this has not already been implemented in the UK for a LONG time, i.e. pre-RIPA 2000, then you are very naive.
Ask anyone who has ever worked on infrastructure at a large UK ISP or exchange (e.g. LINX). Copious secret services systems are already used.
The key difference, the key burden that is being (publicly) demanded in 2012 by the services is real-time! Presumably, this was such a burden to the overall infrastructure of the majority of UK ISPs that they just pushed back when requested... hence the new law proposals.
Ask anyone who has ever worked on infrastructure at a large UK ISP or exchange (e.g. LINX). Copious secret services systems are already used.
The key difference, the key burden that is being (publicly) demanded in 2012 by the services is real-time! Presumably, this was such a burden to the overall infrastructure of the majority of UK ISPs that they just pushed back when requested... hence the new law proposals.