Room 40 was the number of Ewing's room at the Admiralty and it was a name that became associated with code breaking. A lovely memoir of Ewing was written by his son, titled "The man of Room 40", and is available in the Department Library.

In May 1916, Ewing was offered the Vice-Chancellorship of Edinburgh University, which he accepted. That university in its turn also went through a period of unprecedented expansion and development under his leadership. Whilst at Edinburgh, Ewing had a tradition of asking guests to his house to draw (with eyes tightly shut) the outlines of a pig. The results were kept in the 'pig book', many of the results, drawn by such dignitaries as Winston Churchill, Charles Parsons and William Bragg, appearing in the book by his son mentioned above.