Thanks all for such interesting replies.
Max, your comment closely ties in with another comment made by the seller of the eBay ones, that her two came from a tiki bar where the seller's aunt worked - somewhere in the London area. Tiki bar or burger bar - certainly burger bars were very popular in the 60's - the aunt claimed to recall unpacking them from boxes marked Ravenhead (remembered as they had a relative who also worked there). All the eBay info is, of course, unconfirmed hearsay, but a Ravenhead attribution would not be surprising given the timeframe and that they produced commercial barware.
Even if they don't have an exciting provenance I still think they are fun! :lol: