This is a gorgeous original cut glass interior lamps from a Bentley or Rolls-Royce. We think it is from a car made int he 1940s or 1950s but since we are not experts on these cars, we can't say for certain.
What we can say for certain is that this is an absolutely beautiful lamp, with a cut glass lens, heavy nickel-plated brass body and beautifully-made chrome bezel with extremely fine threads. The quality of this lamp is just astounding.
We think it's correct for an R-type or Mk VI Bentley or prehaps a Rolls-Royce Silver Wraith. If you know for sure, please let us know!