Hi Mike, I think these two might help you. The first one, check for the #19693 Omani Government plates. The second is a commercial website.The third one shows WO Payne,in a picture, next to the Omani badge.
Jo
http://plaque.free.fr/as/oman.html
http://www.handembroideryshop.co.uk/acatalog/Oman.html
http://www.diggerhistory.info/pages-vc/payne-vc.htm