OK DFC so where will all these IFR flights go? There is no procedure for IFR flights to land at Battersea. The IFR helicopters flying on the helicopter routes would not be separated from other IFR operations at Heathrow. Therefore the routes would not be available for use. Standard separation would have to be applied between light aircraft under IFR and the airliners. This would severely limit capacity at Heathrow. How long would this situation be allowed to continue? Light helicopters would be charged for that portion of their flights operated under IFR. Would that be financially viable for the operators? The London CTR is not big enough to support the sort of IFR operation that you are suggesting, and even the low level IFR traffic would be subject to far greater delay than SVFR traffic is subject to. If it is not safe to alllow it into the zone, due to capacity constriants or controller workload where would the traffic hold? There would be a huge environmental impact. Then of course there is the question of pilot qualification. I could go on....