Douglas Svend Fletcher is born in Svendborg, Denmark. He enlists for the Royal Australien Air Force in 1943. I presume he was British and not Danish subject.
Douglas Svend Fletcher is born on 11 May 1925 in Svendborg, Denmark. He is the son of captajn Frank Douglas and Lillian Mabel Fletcher. They are married in Sydney on 5 April 1913. From this information I conclude, that Douglas Svend Fletcher is not Danish citizen. 
He enlists for the Royal Australian Air Force on 17 June 1943 in Sydney. He is posted to No. 100 Squadron on 17 July 1945 as part of W/O J K Taylor's crew. He holds the ranks of Flight Sergeant (Navigator "B") at the time of the posting. In the very last part of the war, this crew takes part in several bombing missions in Bristol Beauforts. 
He is discharged on 9 April 1946 at which point he is attached to 100 Squadron holding the rank of Warrant Officer (Navigator). 
- www.ww2roll.gov.au, Svendborg, Sct. Nicolai parish record
- 100 Sqn ORB