It might be of interest to know that I believe, two AIRPROX have been filed in the last three weeks, by civil airliners at an airfield in class "D" airspace against VFR transits across the airfield that passed a little close to them while VFR.
Perhaps that could be part of the problem, combined with the fact that if a pilot gets a TCAS RA he will respond to it, even if the other aircraft is VFR and providing separation against the IFR aircraft. This means that the IFR aircraft inevitably files a MOR and usually has to be repositioned.
When the airspace is as busy as Stansted perhaps the controllers don't want to take the risk?
