Sounds like you may have a bottle dating to between 1955-1967.
Royal Warrants to HM the Queen (Elizabeth II) were mostly issued
in 1955 & 1957, and the "Federal Law forbids..." warning was no longer
required after 1967.
Depending on additional details we can view on the bottle & cap-design,
we should be able to narrow that time span considerably.
Walter C Hurst