Hi thanks for writing in. It sounds like the marks are either British Hallmarks or Pseudo British Hallmarks, the later are quite common in the US.
British Hallmarks mostly contain 3-5 marks, not necessarily aligned or oriented the same. Marks include maker's mark, Town mark, Standard (Purity) mark, Date Letter, and Duty mark.
It is hard to say without seeing the marks, the crown and 18 (if they appear in a shield) sounds like the gold UK standard mark that appears on 18ct GOLD from 1798 - 1974.
EF & Co will be the maker's mark, the manufacturer or individual who registered the mark. Your description does not include a British town mark, which seems a bit odd.
