Terry,
It's actually the foreign administrations rather than the CAA who have made it possible to take a microlight overseas on an NPPL.
Microlight licences are sub-ICAO and don't have to be recognised by other ICAO states. The French for example choose to allow foreign microlight pilots in as long as they have a valid licence from their home country. This was how PPL(A)/Microlight licence holders were able to visit, and NPPL(Microlight) holders now benefit from the same concession.
Since this is purely for microlights, it leaves NPPL (SEP) holders still stuck on this side of the Channel.
The details are
here.