If one is on a TS and the other basic:-
* Pass radar derived traffic info to the one on a TS and if you have time or capacity non radar derived traffic info to the one on a basic (not mandatory) and let the pilots decide on a course of action as per their responsibility.
One on a DS and the other a basic.
* As above, but with deconfliction advise to the one on a DS. Its upto the pilot if he/she wishes to take that advice.
It is not the responsiblilty of the ATCO to offer an upgrade in service. Its up to the pilot to know the terms of the service he/she is receiving and has requested, and to request an upgrade if they want one.
I have read the Forum you mention. Its concerning the lack of understanding still about the service provison of ATSOCAS in the UK. Its been in since last March.
I can understand foreign pilots who maybe visit once in a blue moon. But for UK based pilots its laziness (IMHO). As an ATCO I was required to complete a training program and was tested on the new ATSOCAS prior to its implementation. We still have flying instructors and commercial pilots that regularly fly outside that don't understand the service they have asked for.
Sorry soap box moment at the end.