A foreigner, let's say trained on a Cessna 152, being sent home with an SA licence and having absolutely no idea that they have to be examined by an SA trained and qualified instructor/examiner before they can fly a 150, a Cherokee, a 172 or any other simple light aircraft in their own country.
Just to clarify - the new pilot could fly a 152 in the UK. (Someone managed to misunderstand that quote and got worried!)
One other actual existing problem at the UK end is that one or two UK rental organisations, used to dealing with JAA and FAA licences and 'SEP' legal classes actually convince the new PPL that they can do a type conversion for him/her, not realising that any future incident might have insurance problems when the SA CAA ask 'why was he flying a PA28? - of course, until an incident, everyone happy in ignorance!