halo, the point is light a/c are not difficult to deal with in a Heathrow type environment, we just make it much more difficult than it has to be. Often because many in the system these days, through no fault of their own, have no experience of seeing light a/c in amongst the heavier stuff.
Given reasonable weather a light single operating SVFR would not need any wake vortex separation inbound...it gets vectored to hold on a base leg, gets told its traffic coming down the ILS, reports it in sight, positions visually behind number 2 having been told "caution vortex wake etc", turns in close behind and always above the jet traffic and given the length of the runway lands long and safely. Little time lost in the arrival sequence. There is no rule that says just because it is Class A you can't use reduced separation in the vicinity of an aerodrome
Departing SVFR it doesn't follow a SID, it goes off on a radar heading and aside from probably waiting two minutes behind the departure ahead it is airborne and out the way barely holding the next departure up at all.
We, that is ATC as a group, do tend to have more of a "can't do" than "can do" attitude at times
WF.