I've recently been searching Google for information about Roseberry Topping. There's a local legend that states that King Osmund/Oswald's son, Oswy, was drowned in a spring there. It's said that Oswald's Queen then died of grief soon after and was buried, along with her son, at the nearby village of Osmotherley - hence the name.
I also read that OS is the Anglo-Saxon rune for 'God,' specifically the god Odin. I can't help but wonder if the 'os' in Roseberry is an etymological derivation of this. Or if Roseberry is simply of modern rendering of the name Oswy - Oswy Topping.
Apparently Oswy can also be spelt Oswiu or Oswig.