Shawn, the design of the RAF instrument panel was different; it had a larger extension to the right hand side which made it sit heavier on the right hand flexible rubber "Barry" mount. The panel on many aircraft therefore hung slightly right hand low so the ball sat out to the right in balanced flight. We used to notice it when flying on instruments; if you put the ball "in the middle" the aircraft turned gently right as it was actually yawing.
The simple cure? We always carried an En-route supplement book (containing ATC info, airfield details, frequencies etc), normally in our flight suit lower leg pocket. Suitably jammed under the right lower edge of the panel, it brought the instruments to a true level and put the ball back where it should be.
