In the UK you can comply with IFR at night by flying at or below 3000' amsl, remaining clear of cloud, with the surface in sight (new wording as of Mar 07) and in a flight visibility of at least 800m. Fine.
Choice of IFR or VFR -
At night an aircraft shall fly in accordance with the Instrument Flight Rules outside a control zone.
Inside a control zone an aircraft shall fly in accordance with the Instrument Flight Rules unless it is flying on a special VFR flight.
ATCO Question: Is special VFR flight only available to aircraft landing or taking off from an airport in the control zone or is it available to aircraft transitting the zone?