Does anyone know where I can buy the ‘R’ shaped clip that secures the pin that holds the pads in place on the Saint M810 caliper ?

CRC stock the brakes and some spares, but not the clip.

I have lost one as well. Just about to go and collect my ride from the LBS and will ask them about it when I get there and see if they know where to get some spares from just in case I lose one in the future. If the price is negligable or they give me a load then I will let you know and I can pop one in the post.
Will update you in a bit!

Try here RC body clips

Never bothered about them mind..

I lost mine years ago, but the pin has never worked loose in either brake.

No luck at the LBS. Might just see if a cut down, bent paperclip will work…

Kit, I agree, I dont think the pin will work loose. I just want a spare as if I do loose one it will bug the hell out of me and give me sleepless nights. Im Autistic like that.