 Wilkie was initially employed from 1910 as a surgeon at Leith Hospital, in the harbour area of Edinburgh, and in 1912 moved to Edinburgh Royal Infirmary, as House Surgeon under Harold Stiles.On 26 April 1913, he was commissioned as a surgeon in the Royal Naval Volunteer Reserve (RNVR).During the First World War, he served on the hospital ship "St Margaret of Scotland", first in the Mediterranean and then in Salonika.