The newspaper claims that Sir Guy has "one of the oldest titles in England." Later on he is described as a baronet. King James created the title of baronet in 1611 as a way to raise money for the crown, so there are many other families holding English hereditary titles (duke, earl, baron, count) that are of much older origin.
The unopened letters from Nancy to Don from Paris all have the same date on the cancellation postmark.