Your bottle is most likely very late 1950 or very early 1960, before White Horse went to using clear glass in thier bottles.
The device you describe for holding down the cork is called a "Spring Cap" (Invented in 1929, Patented 1945 under the name Kork-n-Seal)...this device was discontinued from use on White Horse bottles in the very late 1960's.
I've collected these Spring Cap bottles here in the US for a long time (many White Horse among then), and have 2-3 just like it.
Your bottle has a nice fill-level on it, and would fetch $200+ in my collection.
Walter C Hurst