In my experience many countries in the developed world provides FIS from the approach or en-route units using radar derived data. Consequently you can be proactively cleared through airspace easier.
You get that in the UK too, London (or scottish) info is for when you're not in CAS.
Where you are in areas where you cannot get a RAS they are the next best thing as its better to be in contact with someone rather than no one.
That's pretty old school, surely you mean traffic or deconfliction service rather than radar advisory?
Plus, you can ask London info almost anything and they will come up every time. What's the weather in Southampton? Inverness? is whatever danger area active?
And on the day of the last world cup final, the most asked question, "What's the score". He even had the courtesy to add, those who do not wish to know should turn the volume momentarily down now...
When did you ever get such a brilliant service from a radar controller?