Interesting article! I think I found a reference from 1950: https://books.google.co.uk/books?id=fdQvAAAAMAAJ&q=%22100+miles%22%22long+distance%22+%22100+years%22&dq=%22100+miles%22%22long+distance%22+%22100+years%22&hl=en&newbks=1&newbks_redir=0&source=gb_mobile_search&sa=X&ved=2ahUKEwjlz__jkM6BAxUgU0EAHfgUDfQQ6AF6BAgHEAM#%22100%20miles%22%22long%20distance%22%20%22100%20years%22 When googling, there were also a couple of references to Danes (instead of Brits) in the same expression