I've never seen any brits go though BUD/S, not saying they havn't, I just don't know of any.
Other nations have sent some lads over, they will attend the whole gambit, and get a Trident awarded to them after graduation. Yes, it is an honorary gesture, but most of the foreign nationals really earn their bird.
I wouldn't expect to see any SBS or SAS lads attending BUD/S. BUD/S is a beginer school, a kick in the nuts, SBS/SAS guys have already proved their metal and there really is no need to go through this. I have worked with some SBS lads in advanced training and the such, great guys to work with, we learn a lot from each other.
There have been a number of SEALs attending, and graduating selection (NZ, AUS and GB). Team guys have worked with the SBS guys in theater before, we have a very good working relationship with them.
The guy in the picture you posted is a real deal. Super stud French frogman, hard as woodpecker lips.
Thank you for answering my questions - good to see you back :o)