I know Simon Das, he has been in the London Silat scene for a while. If I am not mistaken he was of the same generation as Steve Benitez and Abdurahman the Greek. Simon is also close to Bang Aidinal Al Rasyid (Gerak Ilham Bugis) and he has traveled extensively in Indonesia and Malaysia in search of silat.
Currently he teaches a type of silat Sendeng and something called Silat Kesateria Al Haqq. I have not heard of the King's seal on his certificate, but I know that he is a good instructor who has been diligently studying silat for a while now. He is very open and welcoming. If you would like his mobile number PM me.
Hope this helps.