Is this an UK special question?
As I remember from flying under EU rules on continental Europe, you had to declare some kind of urgency to ATC to be allowed to pick up IFR in flight without prior flight plan. In many cases I heard them say, "land at the nearest airport, file a flight plan for IFR and take off again with it" - same with this night VFR flying. Am I correct, that this AFIL for VFR is now coming with this SERA thingies and that currently the question is only raising in the UK?