Hi...I'm looking for any help in identifying the logo/marking on this Swiss pocket watch movement. The original UK Sterling case dates the watch to approx. 1919. The photo wil hopefully show the unususal mark - a 3 pronged fork with the letters 'R' and 'S' on either side. It's also signed 'Swiss Made' '15 Jewels' and serial number '230330'. Thanks in advance.....D.