Sorry, FBW, that's not right.
Within the UK, all flights must either be IFR or VFR, except that in Rule 21 airspace you must be IFR at all times.
At night, outside a Control Zone, you must fly according to IFR. However, inside a Control Zone you can be IFR or Special VFR. This is Rule 22.
It isn't just Rule 21 (aka Class A) airspace that you can be SVFR in, you can also be SVFR in Class D but it MUST be a Control Zone (i.e. down to ground level). You cannot be SVFR inside a Control Area with a base, nor a TMA.
It is a popular misconception that because someone doesn't have a IR they cannot fly IFR. If you are flying at night outside a Control Zone, immaterial whether you have a Night Rating, then you are IFR. Plain and simple. You have to comply with Rule 29 (Minimum Height) and Rule 30 (Quadrantal Rule) - see Rule 28.
And because 'SVFR' is inside a Control Zone then you do require 'SVFR Clearance'.
[typo corrected]
[This message has been edited by Lew Ton (edited 17 November 2000).]