Hi folks.
Yes ATC ss used to be a radar or identification service and was changed to accomodate ADSB.
There are a couple of ways ATC can clear you for VSA at night.
1. Inside 30nm from destination.
-VFR anytime.
-IFR the pilot has established and can continue flight to the
aerodrome with continuous visual reference to the ground or
water; and the visibility along the flight path is not less than 5000 M
You then must comply with all of the AIP restictions of a VSA
or
If you are being vectored for sequencing/separation or if you are being descended to a radar lowest safe whilst being recieving a surveilance service[ie I am monitoring you on a specific track ] then ATC must assign the min vectoring altitude and give heading or tracking instructions to intercept final or to position the aircraft within the circling area.
The required phrasology is then "when established on the PAPI [or in the circling area] cleared visual approach.
I believe the controller in the origional question is either being lax or doesn't understand the restrictions that they are applying to your descent.
Otherwise they would clear you to track as required for final.
Hope it helps.
AA