How do Driving Instructors Get Accredited?

I was driving south along the M1 today near the Robina on ramp,
driving in the passing lane, when this little car covered in L stickers
merged on to the highway and then proceded to cut across in front of me, because there was a truck in his lane that would have slowed him down, I had to brake to avoid running up his arse, so I flashed the high beams and he waved to me while looking in his rear vision
mirror, so I gave him the finger, next thing he slams the brakes on,
and then speeds off, I followed him till he took the next exit ramp,
and he started waving his mobile phone at me, I usually let the idiots
go and just think he will come to grief sooner or later, but some times
like today you know how people get involved with Road Rage, and
this person was a Driving Instructor, heaven help his Students.

Cheers
Daza