Not exactly, the two-letter DH designator was one of a small series of short-lived two letter designators of
the 1920s-early '30s. The DH designator, per the 1922 standardization, was originally used 1927-1931.
DH aircraft can be confusing because of the use of the DH model number on pre-standardization types,
e.g. DH-4, or adding an X prefix to the model number e.g. XDH-80 for the single D.H. 80 Puss Moth
purchased in 1934 for the USN Attache in London.
The later C for De Havilland Canada was assigned to Otters purchased in 1955-56.
In the WWII period, up to 1946, C was used for Curtiss (21-46), Culver (43-46) and Cessna(43).
Note also that assigment was to
manufacturer not
designer so only De Havilland
built aircraft
would receive the DH or C, as the profiles show with the G designator Goodyear built Sea Hornet.
Fer my money I'd have them built by Canadian Car & Foundry, 1942-45 designator W, and as the first of a type
from a given manufacturer does not have a numeral in the designator, it would be the FW-1,2,3 and on; second
type the F2W-1,2,3 etc.
Greg's suggested AEW variant might be an FW-1W, or an F2W-1W.
An F2W designator would require that the Hornet/Sea Hornet be the second fighter type built by CC&F for the USN,
and there is a way around that. CC&F assembled the Grumman FF-1 under license as the GG-1/G-23 so ...
what if a couple had been bailed back to the USN and designated FW-1? If so, by default the CC&F built Sea
Hornet becomes the F2W.