This doesn't look like any Rigby I have ever seen but it does look like a single square bridge magnum length action, a Rigby bolt peep, an expensive scope mount system, and a low price, depending on what it really is:

"RIGBY375"

That swept bolt handle sure does not look original to that rifle. Something is amiss for certain!

Yeah, there's alot that isn't righteous. The bolt handle, the engraving, the rear sight, the polishing, etc. etc. Someone bought it, none-the-less.