For a while I thought they were called Mickey permits because they were printed in Belfast and not Newcastle. 
Seriously though I was at the Yugoslave border at Subotica one night with another British driver and we compared our two Yugo permits.
The Yugo coat of arms I.I.R.C had like a flower or flames with either six or seven petals each representing one of the old states of the former Yugosalavia.
That was the problem my permit had seven petals and his permit only had six. 