HD, think you might be slightly misinterpreting what was being said. If a controller is vectoring aircraft onto final approach then the wake turbulence seperations are mandatory for the controller to achieve, otherwise the aircraft should be broken off the approach. What is meant is that if an aircraft, whether VFR or IFR is conducting a visual approach then the controller will pass the recommended spacing and it then becomes the pilots decision to achieve or not that recommended spacing.
Dont suppose there are many visual approaches carried out at heathrow most days.
