Respectfully I disagree, it is upto the flight crew to decide the appropriate level of FIS. By giving deconfliction vectors to an aircraft under a traffic service or providing routine traffic information while under a basic all you are doing is blurring the lines of what the pilot can expect from the type of service being provided. By all means if the crew request deconfliction advice or are under vectors for an approach then the ATCO is obliged to assist. The 'duty of care' is fulfilled by passing accurate and timely traffic information to the crew and updating it as necessary. CAP 774 is very clear about the responsibilities of all involved.