Working hard said "The "duty of care" argument oft posed against the above is utter rubbish. How can one have a duty to do something that the written procedures clearly say you do not have to do? - Are the written procedures wrong?"
The 'written procedures' include the following;
3 Control of VFR Flights
3.1 Although in Class D, E, F and G airspace separation standards are not applied, ATC has a responsibility to prevent collisions between known flights and to maintain a safe, orderly and expeditious flow of traffic. This objective is met by passing sufficient
traffic information and instructions to assist pilots to see and avoid each other. It is accepted that occasionally when workload is high, the traffic information passed on aircraft in Class F and G airspace may be generic rather than specific.
3.2 Instructions issued to VFR flights in Class D airspace are mandatory. These may comprise routeing instructions, visual holding instructions and level restrictions in order to establish a safe, orderly and expeditious flow of traffic and to provide for the effective management of overall ATC workload.
3.3 For example, routeing instructions may be issued which will reduce or eliminate points of conflict with other flights, such as final approach tracks and circuit areas, with a consequent reduction in the workload associated with passing extensive traffic
information. Visual Reference Points (VRPs) may be established to assist in the definition of frequently utilised routes and the avoidance of instrument approach and departure tracks.
I think you will find that most ATCOs have no interest in 'separating' VFR from IFR traffic in Class D airspace but given that the above is published in the MATS Part 1, few of us feel we have any alternative than to provide additional safequards/seperation than the basic ICAO definition of Class D may suggest.