FB
Sorry, but I have to differ on this one, at least as far as UK licences are concerned. The ANO Part A (Licences), Section 1 (UK Licences) says:
1 AEROPLANE PILOTS Private Pilot's Licence (Aeroplanes)
(1) Subject to paragraph (2), the holder of the licence shall be entitled to fly as pilot in command or co-pilot of an aeroplane of any of the types or classes specified or otherwise falling within an aircraft rating included in the licence.
(2)
(a) ...
(b) ...
(c) He shall not, unless his licence includes an instrument rating (aeroplane) or an instrument meteorological conditions rating (aeroplanes), fly as pilot in command of such an aeroplane:
(i) on a flight outside controlled airspace when the flight visibility is less than 3km;
(ii) on a special VFR flight in a control zone in a flight visibility of less than 10 km except on a route or in an aerodrome traffic zone notified for the purpose of this sub-paragraph; or
(iii) out of sight of the surface.
Unless Jersey ATZ is 'notified for the purpose ... (?)' I take this to mean that you might be able to use a non-CAA JAA licence to fly SVFR in Class A in less than 10k viz, but not on your CAA licence without an IMC or IR.