Here is a Scott 270 "Cabot Issue" canceled stamp...
The cancel (dual ring) on this Scott 270 Newfound stamp is dated
June 2. 1948. The voting for the referendums to become part of Canada occurred on
June 3. 1948. Which makes it possibly the LRD (Last Recorded Date) of this cancel hours before the referendum began the next morning.

Harmon Field post office
Postmaster – P. Ryan
Date – From 1943- 10-13 to 1949-04-18
In 1940, the town became host to the largest American Air Force Base outside the continental US. Under its Leased Bases Agreement with Britain, the United States had obtained rights to build the Stephenville air base in 1940.
Fig.1 - Shows the Air Base as it was in the 40's
Fig.2 - Shows the actual air field Harmon Field Air force base.
Fig.3 - Map of Harmon Field Air Force base.

FIGURE.1

FIGURE 2

FIGURE 3