Thank you for your response to my query. I have only now figured out how to respond to threads. In answer to your question: the Blazon of the Keys arms was supplied by the office of the Ulster King of Arms to the family in Australia that requested the conformation back in the 1930s. I had contacted the office and was told that no further records on the case were available, and that in any case the office did not do "genealogy". My own research suggests similarities with the old Bright Banner of the Aberach MacKay (not Lord Reay's arms, which were granted in 1628), and possibly the arms of Lamont of that Ilk. In the latter case, even the motto has a similar grammatical structure (Keys: "ne perii nec disperii"). Any further observations would be most welcome.