OK Here is the definitive...(from me - being a night instructor...)
At night non-IMC/IR pilots must fly in ACCORDANCE with IFR - not COMPLIANCE with. These are the terms used by the CAA. There is a difference - mainly that the instrumentation requirements for the aircraft for IFR flight are NOT required.
As per a previous post quite right Schedules 4 & 5 of the ANO.
The ANO does NOT require ANY form of radio navigation aids for ANY aicraft flying in VMC, either in class D airspace or otherwise. The real difference between day and night flying is the need for gyros - and in CAS (class D) there is NO difference to the requirements for flight in that CAS during the day.
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WRT accordance with IFR - moreso for IR/IMC pilots - it is oft misunderstood that you can legally fly visual circuits & approaches under IFR - the problem comes for the ATCO with regard to maintaining minimum aircraft separation distances - but from a pilot's perspective its all more than possible provided VMC is maintained.
At night this means that below 3000' in sight of the surface clear of cloud you are not required to maintain min heights above obstacles - however 'in sight of surface' depends on how much is black and how much isnt - after all - you cant claim in sight of the surface unless you can actually see it...so over most of Wales/Scotland you would be foolhardy if not illegal to maintain an altitude below minimum IFR standards.
Hope this helps!