First Ive heard of it. The one thing that makes me suspicious though is that they say about a villa on the coast of spain and then say how they dont know his name?
In the original story (ages ago), the villa was never mentioned, and no investigative followup story was ever told so no idea if they actually found out what happened here.
My guess is, he was taken on by either the Council or the Zoo and they simply lost or didnt do his paperwork correctly or someone did in fact know about him, because there is no way a man can work 25 years without someone asking who he is employed by.
PS Urban Legend
http://www.snopes.com/crime/clever/carpark.asp