This spring is from the brakes section in the Rolls-Royce & Bentley parts catalogue for models built between 1965 to 2003.
This is the anti rattle spring on the rear calipers. There are two required for each caliper. It's part of the rear brake pad kit CD6396 for cars prior to 1994 available here.
For cars built after 1994 use UR73209 which are available here.
All our parts branded Prestige Parts have a 3 year warranty.