Identify this movie!

I saw this film on TV in France many years ago (likely late 80s). I’m positive it was dubbed from English to French. It was in monochrome, not colour. The scene I recall is near the end, with monks marching into stalls (in a chapel?) and then throwing off their robes and revealing themselves to be knights, possibly with the King present. I thought it was Ivanhoe or Quentin Durward, but the plots of neither ring any bells with regard to that scene, and both of those are in colour.

Help me Dopers!

Could it have been a monochrome version of The Adventures of Robin Hood?.

Just thinking that. It seems to be a standard part of the King Richard story.

That was my first thought but the Errol Flynn version was in Technicolor. Perhaps the later English version? I sure does sound like Robin Hood.

Yeah, that sounds like the kind of stunt that Richard would have pulled. Anything to get John in trouble.