Alan, I'm not disagreeing, but I don't find any link in the ANO between SVFR and it only being available in a CTR. Conversely, the AIP is quite specific and talks only about CTRs. Taking this a step further, the only weather criteria I can find for SVFR refer to in-flight visibility and not contact with the surface (as I am thinking about CTR/CTA transits, I am ignoring to 600ft cloudbase bit for arrivals and departure here). To confuse the issue the AIP says the following:
2.3 When operating on a Special VFR clearance, the pilot must comply with ATC instructions and remain at all times in flight conditions which enable him to determine his flight path and to keep clear of obstacles. Therefore, it is implicit in all Special VFR clearances that the aircraft remains clear of cloud and in sight of the surface. It may be necessary for ATC purposes to impose a height limitation on a Special VFR clearance which will require the pilot to fly either at or not above a specific level.
Note that in sight of the surface bit is "implicit", whatever that means! I can quite happily determine my position and maintain obstacle clearance without seeing the surface. Indeed, I have often offered to take an IFR clearance only to be given a VFR/SVFR one.
As I see things, in theory, you can have a SVFR clearance above cloud through a CTR but not a CTA.
I think I will take a cold flannel and lie down in a dark room now.
