I received this information from Diageo:

"This bottle was produced by Bell's for the US market, and from comparing it to those in our historic bottle collection, I would date it between the early 1950s and early 1960s. I can't be any more specific than this I'm afraid, as Bell's bottles and packaging from this period were only updated/changed about once a decade."

Many thanks to you, Jojo, for your help!