Fuji Abound
What happened to the old 90 degree airways crossing "without full compliance with IFR"?
It's not a SVFR clearance through Airways though. The pilot must hold an IR, it's just that the aircraft cannot meet the IFR requirements (e.g navaid carraige). The crossing must be in VMC in Day only, and controllers will treat the aircraft as though it was IFR. So you can expect to be given a cleared level and be expected to comply with IFR level occupancy rules, as well as any routeing or vectoring instructions required.
VFR does not exist at night in controlled airspace in the UK so if you have a night rating and the viz is 10k or more SVFR is your only option.
Only available in Control Zones. No good in TMA's or Airways.